ESSN EB EN a TNS eR BY SSP SOU MONTY OI UA ACTUATE For NDA & NA EXAMS PHYSICS We have designed these notes based on the syllabus that UPSC provide. This content provide you the exact guidance for you prepration to crack the NDA & NA exam. yy ae ATU1[Pag CONTENT UNIT & MEASUREMENTS OPTICS MOTION FORCE CURRENT ELECTRICITY MAGNETISM GRAVITATION HEAT & TEMPERATURE MECHANICAL PROPERTIES » SOLIDS »~ FLUIDS WORK; POWER. & ENERGY WAVE MOTION & SOUND SIMPLE\HARMONIC MOTION (SHM)2|Page PHYSICAL QUANTITY, ANYTHING THAT CAN BE EXPRESSED IN NUMBERS IS CALLED QUANTITY. EXAMPLE- LENGTH, MASS, TEMPERATURE, TIME, FORCE, SPEED, DISTANCE, ACCELERATION, VELOCITY, MOMENTUM, CURRENT, ETC. TYPES OF PHYSICAL QUANTITIES 1, FUNDAMENTAL/BASE QUANTITY > THOSE QUANTITIES WHICH DO NOT DEPENDS ON THE OTHER PHYSICAL, QUANTITIES EXAMPLE- LENGTH, MASS, ELECTRIC CURRENT}TIME, TEMPERATURE, LUMINOUS INTENSITY, AMOUNT OF SUBSTANCE, 2. DERIVED QUANTITIES > THE QUANTITIES WHICH ARE DERIVED FROMTHE FUNDAMENTAL QUANTITIES, EXAMPLE- WORK, FORCE, PRESSURE, AREA, VOLUME, ENERGY. 3, SUPPLEMENTARY QUANTITY > SUPPLEMENTARY UNITS ARE THE DIMENSIONLESS UNITS THAT ARE USED. ALONG WITH THE BASE UNITS TO FORM DERIVED UNITS IN THE INTERNATIONAL SYSTEM > SUPPLEMENTARY QUANTITIES ARE GEOMETRICAL QUANTITIES OF CIRCLE AND SPHERE. ON THE BASIS OF DIRECTION & MAGNITUDE, 1, SCALAR QUANTITY, ASCALAR QUANTITY IS DEFINED AS THE PHYSICAL QUANTITY THAT HAS ONLY MAGNITUDE. \_ EXAMPLE: DISTANCE, ENERGY. POWER, TIME, SPEED, DENSITY, PRESSURE, WORK, CHARGE, ELECTRIC CURRENT, TEMPERATURE, MASS, FREQUENCY, SPECIFIC HEAT. 2. VECTOR QUANTITY AVECTOR QUANTITY IS DEFINED AS THE PHYSICAL QUANTITY THAT HAS BOTH MAGNITUDE AS WELL AS DIRECTION. > EXAMPLE: DISPLACEMENT, VELOCITY, TORQUE, POSITION, ACCELERATION, FORCE, WEIGHT, MOMENTUM, IMPULSE, ELECTRIC FIELD, MAGNETIC FIELD, (CURRENT DENSITY, ANGULAR VELOCITY3|Page UNIT UNIT IS THE QUANTITY OF A CONSTANT MAGNITUDE WHICH IS USED TO MEASURE, THE MAGNITUDES OF OTHER QUANTITIES OF THE SAME NATURE, PHYSICAL QUANTITY = (NUMERICAL VALUE) » (UNIT). FUNDAMENTAL UNIT. THE UNIT OF FUNDAMENTAL PHYSICAL QUANTITY IS CALLED FUNDAMENTAL, UNIT. > SEVEN FUNDAMENTAL UNITS ARE: METER (M) I. KILOGRAM (KG) m. — SECOND(S) Iv. AMPERE (A) Vv. KELVIN (kK) vi. CANDELA (CD) vil. MOLE (MOL) > THESE QUANTITIES ARE INDEPENDENT OF EACH OTHER DERIVED UNITS > UNITS OF ALL OTHER PHYSICAL QUANTITIES EXCEPT FUNDAMENTAL, PHYSICAL QUANTITIES WHICH ARE OBTAINED WITH THE HELP OF FUNDAMENTALS UNITS > EXAMPLE: UNITS OP‘AREA, DENSITY, SPEED, WORK, FORCE, ENERGY, ACCELERATION, MOMENTUM SUPPLEMENTARY UNITS, > \ THE UNITS USE FOR SUPPLEMENTARY QUANTITIES. > \EXAMPLE®UNITS OF PLANE ANGLE AND SOLID ANGLE, SYSTEM OF UNITS, 1, MKS SYSTEM 2. CGS SYSTEM 3. FPS SYSTEM 4. SISYSTEM FUNDAMENTAL UNIT AND THEIR SYMBOL, ‘SYMBOL NAME BASE QUANTITY4|Poge M METER LENGTH A AMPERE, ELECTRIC CURRENT MOL MOLE AMOUNT OF SUBSTANCE, SUPPLEMENTARY UNITS AND THEIR SYMBOLS UNIT PHYSICAL QUANTITY ‘SOLID ANGLE ‘STERADIAN IMPORTANT FORMULA OF DERIVED UNITS,S|Page TIME METRIC PREFIX FOR PO! - : 7 : WER 10 ZETTA 107 Zz 1 ATTO 101 A YOCTO 1024 M4 SS DIMENSIONS OF PHYSICAL QUANTITIES6|Page MASS{M1 LENGTHIL) TIME] ELECTRIC CURRENTA] TEMPERATUREAK] LUMINOUS: INTENSITY{CD] AMOUNT OF SUBSTANCE{MOL] DIMENSIONS TABLE DERIVED DIMENSIONS SI. UNIT SYMBOL QUANTITY, 1 AREA [Lemors] SQUARE METER Me 2 VOLUME [LsmeTo] CUBIC METER Me KILOGRAM PER 3 DENSITY [LsM'T] KG/M? ‘CUBIC METER 4 VELOCITY Lier] METERPER SECOND M/S METERPER SQUARE 5 ACCELERATION [L'MeT2] M/S? SECOND KILOGRAM METER 6 = MOMENTUM lim KG M/S PER SECOND 7 _ FORGE! Iui't2) NEWTON N 8 IMPULSE ('M'T'] NEWTON SECOND NS 9 \ WORK [LeM'T2] JOULE J 10 KINETIC ENERGY (L2m'T?] JOULE J POTENTIAL "1 Lem'r] JOULE J ENERGY 12 POWER [Lem'Ts] WATT w7|Page 13 14 15 16 PRESSURE [e'm'T4] ELECTRIC CHARGE [L°M°T'I'] ELECTRIC CURRENT ELECTRIC POTENTIAL (eM! T"] [lems] NEWTON PER N/M2 SQUARE METRE ‘COULOMB c OHM 2 VOLT v8 Page > ITISTHE BRANCH OF SCIENCE IN WHICH WE STUDY ABOUT LIGHT AND ITS. PROPERTIES, NATURE ETC. # CLASSIFIED INTO TWO TYPES 1. RAY OPTICS- DEALS WITH LIGHT RAYS LINEAR PROPAGATION OF LIGHT SUCH AS REFLECTION, REFRACTION, DISPERSION ETC 2. WAVE OPTICS- DELAS WITH WAVE NNATURE OF LIGHT SUCH AS. POLARISATION, DIFFRACTION LIGHT > FORM OF ENERGY THAT MAKES US TO SEE. > AN OBJECT REFLECTS THE LIGHT THAT FALLS ON IT. THIS REFLECTED LIGHT, WHEN RECEIVED BY OUR EYES, ENABLES USO SEE > WE ARE ABLE TO SEE THROUGH A TRASNPARENT MEDIUM AS LIGHT IS. TRANSMITTED THROUGH IT > — SPPED OF LIGHT-3°108M/S # PROPERTIES OF LIGHT > IT TRAVELS IN A‘STRAIGHT,LINE + ASTRAIGHT LINE'DRWAN IN THE DIRECTION OF PROPAGATION OF LIGHT IS CALLED A RAY.OF LIGHT > | ABUNDLE OF ADJACENT LIGHT RAYS IS CALLED BEAM OF LIGHT >| SPEED OF LIGHTN VACCUM IS 3°10°M/S, BUT DIFFERENT IN DIFFERENT MEDIA — \ THE SPEED AND WAVELENGTH OF LIGHT DECREASES WHEN IT TRAVELS FROM (QNE MEDIUM TO ANOTHER BUT ITS FREQUENCY REMAINS UNCHANGED SPPED OF LIGHT IN SOME MEDIUM MEDIUM ‘SPEED OF LIGHT VACCUM STO M/S WATER 2.25°10°M/S OIL OF TARPIN 2.04108 M/S GLASS 21108 M/S. ROCK SALT 1.96108 M/S NYLON 1.96°10° M/S9|Page = SHADOW WHEN AN OPAQUE BODY IS PLACED IN FRONT OF SOURCE OF LIGHT LIKE THE, SUN, THEN BEHIND THE OPAQUE BODY A BLACK OR DARK REGION APPERAS WHICH IS CALLED SHADOW TYPES OF SHADOW DEPENDS ON THE TYPES OF SOURCES OF LIGHT 1, UMBRA- SOURCES OF LIGHT IS POINT SOURCE 2. PENUMBRA: FOR AN EXTENDED SOOURCE OF LIGHT ECLIPSE ‘SOLAR ECLIPSE: WHEN THE MOON COMES B/W THE SUN AND THE EARTH, THEN THE SHADOW OF THE MOON FALLS UPON THE EARTH AND FORM SHADOW REGION THE SUN IS NOT VISIBLE, ON FULL MOON LUNAR ECLIPSE: WHEN THE EARTH COMES B/W THE SUN AND THE MOON, THEN THE SHADOW OF THE EARTH FALLS ON THE MOON, THEN THE SHADOW, REGION @F/THE MOON IS NOT VISIBLE AND THIS POSITION IS CONSIDERED AS WUNAR.ECLIPSE ON'NEW MOON NOTE: ECLIPSE DO NOT OCCUR EACH AND EVERY MONTH BECAUSE THE EQUITORIAL ORBIT OF THE EARTH MAKES AND ANGLE OF 50 TO 70 DEGREE WITH THE AXIAL AXIS OF MOON = # REFLECTION OF LIGHT THE PHENOMENON OF REBOUNCING BACK OF LIGHT RAYS IN SAME MEDIUM. ON STRIKING A SMOOTH SURFACE, IS CALLED REFLECTION OF LIGHT LAW OF REFLECTION10| Page 1, INCIDENT RAY, REFLECTED RAY AND NORMAL ALL LIE IN THE SAME, PLANE, 2. ANGLE OF INCIDENCE IS EQUAL TO ANGLE OF REFLECTION. + SILVER METAL IS THE ONE OF THE BEST REFLECTORS, > LAWS OF REFLECTION APPLY TO ALL KINDS OF REFLECTING SURFACE, Mirror reflection Specular reflection _ Diffuse reflection Incident ray Normal Reflected ray eget sage ot saaiaee PLANE MIRROR > IMAGE FORMED BY PLANE MIRROR IS ALWAYS VIRTUAL, ERECT AND EQUAL IN SIZE TO THE OBJECT > THE IMAGE FORMED IS FAR BEHIND THE MIRROR AS THE OBJECT IS INFRONT OF IT + LINEAR MAGNIFICATION = NOTE + THE MINIMUN SIZE OF THE MIRROR REQUIRED TO SEE THE FULL IMAGE OF AN OBSERVERS THE\HALF OF THE HEIGHT OF THE OBSERVER + AF THE PLANE MIRROR IS ROTATED IN THE PLANE OF INCIDENCE BY AN ANGLE, 0, THEN THE REFLECTED RAY ROATES BY ANGLE > \FOCAL LENGTH: INFINITE, POWER-O WHEN TWO MIRRORS ARE FACING EACH OTHER AT AN ANGLE @ AND AN OBJECTS PLACED B/W THEM + 1, NUMBER OF IMAGES GIVEN BY N= 360/@-1, IF 360/@ IS EVEN OR OBJECT LIES SYMMETRICALLY 2. NUMBER OF IMAGES IS GIVEN BY N= 360/@, IF 360/@ IS ODD OR OBJECT LIES ASYMMETRICALLY SPHERICAL MIRROR 1, CONCAVE MIRROR 2. CONVEX MIRROR11| Page IMAGE IF LIGHT RAYS COMING FROM A POINT AFTER REFLECTION MEET AT ANOTHER POINT OR APPEAR TO COME FROM ANOTHER POINT, THEN THE SECOND POINT IS CALLED THE IMAGE OF THE FORST POINT TYPES OF IMAGE 1. REAL IMAGE: IF THE LIGHT RAYS COMING FROM A POINT ACTUALLY, MEET. AFTER REFLECTION 2. VIRTUAL IMAGE: IF THE LIGHT RAYS COMING FROM A POINT, AFTER REFLECTION DOES NOT MEET ACTUALLY, BUT APPEAR TO COME FROM) ANOTHER POINT NOTES — IF HALF OF THE MIRROR IS COVERED, THEN IMAGE FORMED IS'\COMPLETE BUT ITS INTENSITY REDUCES(BECAUSE LESS AMOUNT OF LIGHTIIS REFLECTED FROM THE MIRROR) Image formed by Concave Mirror: Position | Position | nature Ray of or ‘of object image | image diagram Real, Inverted, mat At =a c iP infinity focus diminished Between | inverted a Fandc and Giip AL ate uw Beyond | inverted ce iP Between c ‘and Fand C oaned a (Ate12| Page Convex mirror Ray diagram Object position Image position Nature of image @ Between infinity and the pole Behind the mirror between the focus and the pole Virtual, smaller and erect © a Infinity At infinity Behind the mirror at the focus F Virtual, point-sized and erect USES OF MIRRORS. 1, PLANE MIRRORS: + LOOKING GLASS > USED IN MAKING PERISCOPES WHICH IS USED SUBMARINES, + USED AT BLIND TURNS OF SOME BUSY ROADS, TO SEE THE VEHICLES COMING FROM OTHER SIDE ~ USED TO MAKE KALEIDOSCOPE, A TOY WHICH / PRODUCES BEAUTIFUL, PATTERNS FROM COLOURED PAPER, PIECES OF GLASS OR SMALL COLOUR BEADS 2. CONCAVE MIRRORS > USED IN TORCHES, SEARCHLIGHT, VEHICLES HEADLIGHTS TO GET POWERFULL PARALLEL BEAMSOF LIGHT > SHAVING MIRRORS\TO SEE LARGE IMAGE OF FACE >| DENTIST TO SEE'LARGE IMAGES OF TEETH > \TO CONCENTRATE SUNLIGHT TO PRODUCE HEAT IN SOLAR FURNACES 3. CONVEX MIRROR + USED AS REAR VIEW MIRRORS IN VEHICLES BECAUSE THEY ALWAYS GIVE AN ERECT IMAGE AND HAVE WIDER FIELD OF VIEW AS THEY ARE CURVED OUTWARDS > ASSHOP SECURITY MIRRORS, MIRROR FORMULA AND LINEAR MAGNIFICATION 11113| Page # MAGNIFICATION: THE RATIO OF SIZE OF THE IMAGE FORMED BY A SPERICAL MIRROR TO THE SIZE OF THE OBJECT Image Size Object Size + MP1, IMAGE ENLARGED -» M&1, IMAGE DIMINISHED -» M=1, IMAGE SAME, REFRACTION OF LIGHT > CHANGE IN PATH OF LIGHT RAY AS IT PASSES FROM ONE ME! TO ANOTHER > RARER TO DENSAR-TOWARDS THE NORMAL > DENSAR TO RARER-AWAY FROM THE NORI ‘O ITERS A DENSAR MEDIUM, ITS SPEED REDUCES AND IT BENDS ‘HE NORMAL AND WHEN IT ENTERS RARER MEDIUM, ITS SPEED INCREASES AND IT BENDS AWAY FROM THE NORMAL, # EVERYDAY SCIENCE > THE BOTTOM OF A TANK OR POND CONTAINING WATER APPEARS TO BE RAISED > THE LETTERS APPEAR RAISED WHEN VIEWED THROUGH A GLASS SLAB PLACED OVER A DOCUMENT > APENCIL PARTIALLY IMMERSED IN WATER APPEARS TO BE BROKEN14|Page + ALEMON KEPT IN WATER IN A GLASS APPEARS TO BE BIGGER REFRACTIVE INDEX > THE RATION OF SPEED OG LIGHT IN VACUUM TO THE SPEED OF LIGHT IN ANY MEDIUM > THE REFRACTIVE INDEX OF A MEDIUM RELATIVE TO ANOTHER MEDIUM, IS KNOWN AS THE RELATIVE REFRACTIVE INDEX. LAWS OF REFRACTION # SNELL'S LAW I. THE INCIDENT RAY, REFRACTED RAY AND.NORMAL ALL THREE LIE IN SAME PLANE, Il, THE RATION OF SIN OF ANGLE OF INCIDENCE\TO THE SINE OF ANGLE OF REFRACTION REMAINS CONSTANT FOR A PAIR OF MEDIA, = constant REFRACTION BY SPHERICAL LENSES, + LENS IS A TRANSPARENT MEDIUM BOUNDED BY TWO SURFACES OF WHICH, ONE OR BOTH SURFACES ARE SPHERICAL, lL CONVEX LENS Il, CONCAVELENS CONVEX LENS >| CONVERGING'LENS ~ \ THICKERIAT THE CENTRE AND THINNER AT ITS END jouble convex Lens (t) Plano-convex Lens (c) Concavo-convex Lens15| Page CONCAVE LENS > THINNER AT CENTRE AND THICKER AT ITS END. > DIVERGING LENS ~ ITDIVERGES A PARALLEL BEAM OF LIGHT RAYS PASSING THROUGH IT (a) Double Concave (b) Plano-concave _—_{(c) Convexo-concave Lens Lens Lens # TERMS RELATED TO LENSES: 1 OPTICAL CENTRE i, CENTRE OF CURVATURE, ml, RADII OF CURVATURE IV. PRINCIPAL AXIS Vv. PRINCIPAL FOCUS vi. FOCAL LENGTH vi APERTATURE IMAGE,;FORMATION # CONVEXLENSES: 1) When object is placed beyond 2F. The image is : + formed between F, and 2F, + real and Inverted + diminished 2) When the object is placed at 2F, The image is : + formed at 2F, + real and Inverted + same size as the object 3) When the object is placed between F, and 2F, The image is : + formed beyond 2F, + real and Inverted + magnified16| Page 4) When the object is placed at F, The image is : + formed at infinity + real and inverted + magnified 5) When the object is placed between F, and O: The image is : + formed on the same side of the lens + virtual and erect + magnified 6) When the object is placed at Infinity The image is : + formed at F, + real and inverted me a + highly diminished # CONCAVE LENSES 1) When object is placed at infinity Image is : + formed at F, + virtual and erect + highly diminished Therefore for all positions, image is : + on the same side of object + virtual and erect + diminished LENS FORMULA LINEAR MAGNIFICATION > THE RATION OF HEIGHT OF IMAGE TO HEIGHT OF OBJECT image Height _v object Height u17 [Page +> M=+(VIRTUAL) +> M=4REAL) BEHAVIOUR OF LENS IN A LIQUID > IF LENS IS IMMERSED IN A LIQUID WHOSE REFRACTIVE INDEX WITH RESPECT TO AIR IS MORE THAN THE REFRACTIVE INDEX OF MATERIAL OF THE LENS WITH RESPECT TO AIR, THEN FOCAL LENGTH BECOME NEGATIVE. THAT MEANS THA NATURE OF LENS WILL BE CHANGE, IN SUCH A MEDIUM, CONVEX LENS WILL BE BEHAVE LIKE CONCAVE AND.VICE, VERSA. > IF LENS IS IMMERSED IN A LIQUID WHOSE REFRACTIVE INDEX WITH. RESPECT TO AIR IS EQUAL TO THE REFRACTIVE INDEX OF MATERIAL OR|LENS WITH RESPECT TO AIR, THEN FOCAL LENGTH OF THELENS WILL BEGOME INFINITE, IT WILL BEHAVE LIKE PLANE GLASS SHEET, ALSQIN SUCH MEDIUM LENS WILL BECOME INVISIBLE ATMOSPHERIC REFRACTION > THE EARTH'S ATMOSPHERE IS NOT UNIFORM THROUGHOUT, ITS DENSITY GOES ON CHANGING AS WE MOVE UPTO DOWN. + _ ITCAN BE CONSIDERED TO BE CONSISTED OF WAYERS OF DIFFERENT DENSITIES, WHICH ACTS AS RARER OR DENSAR MEDIUM WITH RESPECT TO ONE ANOTHER > THE REFRACTION OF LIGHT DUE TO THESE LAYERS IS ATMOSPHERIC REFRACTION PHENOMENON BASED ON\ATMOSPHERIC REFRACTION 1, TWINKEING OF STARS 2. THE STARS.SEEM HIGHER THAN ACTUALLY APPEAR 3. ADVANCE SUNRISE AND DELAYED SUNSHET 4) SUN'APPEARS FLATTERED AT THE SUN RISE AND SUNSHET 1, TWINLING OF STARS > DUE TO ATMOSPHERIC REFRACTION OF STARS > AS THE LIGHT FROM THE STARS ENTERS THE EARTH'S ATMOSPHERE, IT UNDERGOES REFRACTION DUE TO VARYING OPTICAL DENSITY OF AIR AT VARIOUS ALTITUDES ~ THE CONTINUOSLY CHANGING ATMOSPHERE REFRACTS THE LIGHT BY DIFFERERNT AMOUNTS. IN THIS WAY, THE STAR LIGHT REACHING OUR18 | Page EYES INCREASE AND DECREASE CONTINUOSLY AND THE STARTS APPEARS TO TWINKLE AT NIGHT 2. THE STARS SEEM HIGHER THAN THEY ACTUALLY APPEAR, > AS THE LIGHT FROM A STAR ENTERS THE EARTH'S ATMOSPHERE, IT UNDERGOES ATMOSPHERIC REFRACTION)AND BENDS TOWARDS THE NORMAL POSITION EACH TIME" + THE UPPER LAYERS OF ATMOSPHERE ARE RARER THAN THE LOWER LAYERS. THE APPARENT ROSITION OF STAR IS ALIGHTLY DIFFERENT FROM ITS’ACTUAL POSITION. > THESTARS\APPEARS SUGHTLY HIGHER THAN ITS ACTUAL POSITION, WHEN VIEWED NEAR HORIZON ; wre ek Light ray path 3. ADVANCE SUNSHET AND DELAYED SUNSET + THE SUNS VISIBLE TO US ABOUT TWO MINUTES BEFORE THE ACTUAL SUNRISE, AND ABOUT TWO MINUTES AFTER THE ACTUAL SUNSHET. THIS IS BECAUSE OF ATMOSPHERIC REFRACTION19| Page > WHEN THE SUN IS SLIGHTLY BELOW THE HORIZON, THE SUNLIGHT ‘COMING FROM LESS DENSE TO MORE DENSEAIR, IS REFRACTED. DOWNWARDS > BECAUSE OF THIS THE SUN APPEARS TO BE RAISED ABOVE THE HORIZON ead Ded prety Ceara Cerra Sion SCATTERING OF LIGHT. >» THE REFLECTION OF LIGHT FROM AN COMPARABLY SMALLER SIZED PARTICLE IN ALL DIRECTIONS, ~ THE COLOUR OF SCATTERED LIGHT DEPENDS ON THE SIZE OF SCATTERING PARTICLES + VERY FINE PARTICLES SCATTER MAINLY BLUE LIGHT WHILE PARTICLES OF LARGER SIZE SCATTER LIGHT OF LONGER WAVELENGTH(RED LIGHT) + IF THE SIZB OF THE SCATTERING PARTICLES IS LARGE ENOUGH THEN THE SCATTERED LIGHT MAX EVEN APPEAR WHITE, + THE BLUE'LIGHT PRESENT IN SUNLIGHT IS SCATTERED 10 TIMS MORE THAN THE RED.LIGHT. WHY IS THE COLOUR OF THE SKY BLUE? 4) SKY APPEARS BLUE THIS IS BECAUSE THE SIZE OF THE PARTICLES IN THE ATMOSPHERE IS SMALLER THAN THE WAVELENGTH OF VISIBLE LIGHT, SO THEY ARE’MORE EFFECTIVE IN SCATTERING THE LIGHT OF SHORTER WAVELENGTH(BLUE) > WHEN THE SUNLIGHT PASSES THROUGH THE ATMOSPHERE THE FINE. PARTICLES SCATTER THE BLUE COLOUR MORE STRONGLY THAN RED > THE SCATTERED BLUE LIGHT REACHES OUR EYE NOTE + THE SKY APPEARS BLACK TO THE PASSANGER FLYING AT HIGHER ALTITUDESS BECAUSE SCATTERING OF LIGHT IS NOT PROMINENT AT SUCH HEIGHT DUE TO. THE ABSENCE OF PARTICLES20| Page COLOUR OF THE SUN AT SUNRISE AND SUNSHET > SUNAND THE SKY APPEARS RED > LIGHT FROM THE SUN NEAR THE HORIZON PASSES THROUGH THICKER LAYERS. OF AIR AND COVERS LARGER DISTANCE IN THE ATMOSPHERE BEFORE REACHING OUR EYES, > NEAR THE HORIZON MOST OF THE BLUE LIGHT AND SHORT WAVELENGTHS, ARE SCATTERED AWAY BY THE PARTICLES > THEREFORE THE LIGHT THAT REACHES OUR EYES IS OF LONGER WAVELENGTHS, NOTE > HOWEVER AT THE NOON, THE LIGHT FROM THE SUN OVERHEADWOULD: TRAVEL RELATIVELY SHORTER DISTANCE, + SOIT APPEARS WHITE AS ONLY A LITTLE OF THE, BLUE AND VOILET COLOURS ARE SCATTERED Blue scattered away Sun appears reddish nenone AE Less blue scattered WHY RED COLOUR ISUSED IN SIGNAL? + _[FISNOT SCATTERED AS COMPARED TO OTHER COLOURS, | REACHES TO OUR EYES FROM LONG DISTANCE HUMAN EYE AND ITS DEFECT HUMAN EYE, ~ THE SENSE ORGAN THAT HELPS US TO SEE + LOCATED IN EYE SOCKETS IN SKULL > DIAMETER OF EYE BALL-2.3CM. PARTS OF HUMAN EYE # CORNEA- OUTERMOST, TRANSPARENT PART. IT PROVIDES MOST OF THE REFRACTION OF LIGHT= an = 21|Page # LENS- COMPOSED OF A FIBROUS JELLY LIKE MATERIAL. PROVIDES THE FOCUSED REAL AND INVERTED IMAGE OF AN OBJECT ON THE RETINE, NATURE OF LENS-CONVEX LENS, # IRIS-A DARK MUSCULAR DIAPHRAGM THAT CONTROLS THE SIZE OF PUPIL # — PUPIL- WINDOW OF THE EYE, CENTRAL APERTURE IN IRIS FUNCTION OF IRIS- REGULATES AND CONTROLS THE AMOUNT OF LIGHT. ENTERING THE EYE # RETINA-A DELICATE MEMBRANE HAVING ENORMOUS NUMBER OF ‘LIGHT SENSITIVE CELLS IMAGE FORMATION-RETINA # FAR POINT- THE MAXIMUM DISTANCE AT WHICH OBJECTGAN BE SEEN CLEARLY IS FAR POINT OF THE EYE FOR A NORMAL EYE FAR POINT= INFINITE, # NEAR POINT OR LEAST DISTANCE OF DISTINCT VISION-THE MINIMUM DISTANCE, AT WHICH OBJECTS CAN BE SEENMOST DISTINETIVELY WITHOUT STRAIN > FORA NORMAL ADULT EYE-25CM) # RANGE OF EYE —25 CMINFINITE, POWER OF ACCOMODATION > THE BILITY OF AN EYE.LENS TO ABJUST ITS FOCAL LENGTH IS CALLED ACCOMODATION /FOCALLENGTH CAN BE CHANGED WITH THE HELP OF CILIARY MUSCLES # \ FOCAL LENGTH INCREASE: CILIARY MUSCLES GET RELAXED AND LENS GET THIN # FOCAL-LENGTH DECREASE- CILIARY MUSCLES GET CONTACT AND LENS GET THICK DEFECT OF VISION MYOPIA HYPERMETROPIA PRESBIOPIA CATARACT ASTIGMATISM SPep >2|Page MYOPIA. > NEAR/SHORT SIGHTEDNESS, > CAN SEE NEARBY OBJECT CLEAR > BUT CANNOT SEE DISTANT OBJECT # CAUSE 1. EXCESIVE CURVATURE OF THE EYE LENS. ll. ELONGATION OF THE EYE BALL # CORRECTION 1. LENSE-THIICK-THIN I. CONCAVE LENS i. DIVERGING LENS Iv. LESS THE CONVERGING POWER V. BRING THE IMAGE BACK ON RETINA. Rays trom cient Sojact Far point of myopic ove HYPERMETROPIA, + PAR/UONG SIGHTEDNESS + CAN SEE DISTANT OBJECTS + CANNOT SEE NEARBY OBJECTS + APERSON HAS TO KEEP A READING MATERIAL MUCH BEYOND 25 CM FROM THE EYE # CAUSE 1. FOCAL LENGTH OF EYE LENS IS TOO LONG23| Page I, LOW CONVERGING POWER il, EYEBALL HAS BECOME TOO SMALL # CORRECTION 1. CONVEX LENS ll. INCREASE CONVERGING POWER i, BRING THE IMAGE ON RETINA PRESBYOPIA hw THE EYE-LENS: MODATION 1A AND HYPERMETROPIA, HAPPENS IN OLD AGE CILIARY MUSCLES WEAK, CAN Ni SPECIAL KIND OF HYPERME! ett did24a| Page CATARACT > LOSS OF VISION OF EYE > DECREASE IN VISION # SYMPTOMS u. FADED COLOURS i. BLURRY VISION Iv, DOUBLE VISION v. AGEIS COMMON FACTOR # CORRECTION 1, SURGERY ASTIGMATISM, + EYE DOES NOT FOCUS LIGHT ON RETINA, + DISTORTED VISION > BLURRED VISION > EYE STRAIRS, HEADACHE + IRREGULAR CURVATURE OF CORNEA 1.E., ERROR IN THE SHAPE OF THE, ‘CORNEA # CORRECTION > EYE GUASSES-CONTAIN CYLINDRICALL GLASSES IT PROVIDES ADDITIONAL POWER IN SPECIFIC PARTS OF THE LENS CONTAGT LENS SURGERY ++ TOTAL INTERNAL REFLECTION > WHEN ALIGHT RAY, TRAVELLING FROM A DENSER MEDIUM TOWARDS A RARER MEDIUM IS INCIDENT AT THE INTERFACE AT AN ANGLE OF INCIDENCE GREATER THAN CRITICAL ANGLE, THEN LIGHT RAYS ARE REFLECTED BACK INTO THE, DENSER MEDIUM .THIS PHENOMENON IS CALLED TOTAL INTERNAL. REFLECTION25|Page NECESSARY CONDITION FOR TIR 1. THE RAY INCIDENT ON THE INTERFACE OF TWO MEDIA SHOULD TRAVEL, FROM DENSAR MEDIUM TO RARER MEDIUM 2. THE ANGLE OF INCIDENCE SHOULD BE GREATER THAN CRITICAL ANGLE FOR THE TWO MEDIA CRITICAL ANGLE + THE ANGLE OF INCIDENCE IN A DENSAR MEDIUM FOR WHICH THE ANGLE OF REFRACTION IN RARER MEDIUM BECOMES 90 DEGREE IS CALLED CRITICAL ANGLE(C) > THE VALUE OF CRITICAL ANGLES DEPENDS ON THE NATURE OF TWO MEDIA AND COLOUR OF LIGHT ‘When the angle of incidence equal “When the angle of incidence is ‘the critical angle, the angle greater than the critical angle, all refraction is 90-degrees. the light undergpes reflection. APPLICATIONS OF TIR, 1 fOPTICAL FIBRE 2\MIRAGE 3, DIAMOND OPTICAL FIBRE + \ WORKING-BASED ON TIR + INNER PART-CORE OF HIGHER REFRACTIVE INDEX SURROUNDED BY ANOTHER LAYER OF GLASS OF LOWER REFRACTIVE INDEX ~ WHEN LIGHT ENTERS FROM THE ONE END OF THE CORE AND MOVES TOWARDS CLADDING, THAN TIR TAKES PLACE AGAIN AND AGAIN, AND LIGHT. PROPOGATES THROUGH IT USES OF OPTICAL FIBRE + USED TO SEND AN ELECTRICAL SIGNAL BY TRANSFORMING IT INTO A LIGHT SIGNAL AND VICE-VERSA26| Page a USED TO SEND LASER LIGHT RAYS INSIDE THE HUMAN BODY USED IN TELECOMMUNICATION USED IN DECORATIVE TABLE LAMPS, USED IN NETWORKING MIRAGE, AN OPTICAL ILLUSION OF WATER APPEARS IN DESERT IN A HOT SUMMER DAY IN HOT SUMMER DAY IN DESERT THE LAYERS OF AIR NEAR THE EARTH. SURFACE REMAINS HOT AND THEIR TEMP DECREASES WITH ALTITUDE AND BECOME DENSER WHEN A RAY LIGHT COMING FROM THE TOP OF A TREE OR SKY, MOVES, TOWARDS THE EARTH AND DEVIATES AWAY FROM THENORMAL WHEN AN ANGLE OF INCIDENCE BECOMES GREATER THAN CRITICAL ANGLE TIR TAKES PLACE AFTER THAT LIGHT RAYS BEND UPWARD WHEN THE LIGHT RAYS ENTER THE\EYES OFAN OBSERVER, INVERTED IMAGE OF TREE IS OBTAINED WHICH PRODUCES ILLUSION OF WATER Formation of an inferior image DIAMOND BRILLIANCE OF DIAMOND IS MAINLY DUE TO TIR OF LIGHT INSIDE THEM THE CRITICAL ANGLE FOR DIAMOND AIR INTERFACE IS VERY SMALL, THEREFORE ONCE LIGHT ENTERS THE DIAMOND, IT IS VERY LIKELY TO UNDERGO TOTAL INTERNAL REFLECTION27| Page a BRILLLIANCE OF DIAMOND DEPENDS ON ITS CUTTING .BY CUTTING THE DIAMOND SUITABLY; MULTIPLY TOTAL INTERNAL REFLECTIONS CAN BE MADE TO OCCUR. COLOUR OF OBJECT = WHEN LIGHT IS INCIDENT ON AN OBJECT, IT REFLECTS ONLY A PART OF IT. THE REFLECTED LIGHT GIVES THE OBJECTS WITH THEIR COLOURS. EXAMPLE- A ROSE APPEARS RED WHEN WHITE LIGHT IS INCIDENT ON IT. WHEN SAME ROSE IS VIEWED IN GREEN LIGHT, IT APPEARS BLACK BECAUSE IT ABSORBS GREEN LIGHT AND REFLECTS NO COLOUR OF LIGHT COLOURS PRIMARY —RED, GREEN, BLUE, 'SECONDARY- > YELLOW= RED+GREEN, + MAGENTA= RED+BLUE > CYAN= GREEN +BLUE ‘COMPLEMENTARY COLOURS- > RED+CYAN= WHITE, > GREEN+MAGENTA=WHITE, > BLUE+YELLOW= WHITE, PRISM A PORTION OF TRANSPARENT MEDIUM BOUNDED BY TWO PLANE FACES INCLINED TOXEAGH OTHER AT SUITABLE ANGLE WHEN ALIGHT IS INCIDENT ON PRISM THEN IT BENDS TOWARDS ITS BASE LE., IT REFRACTS THE LIGHT28| Page DISPERSION OF WHITE LIGHT BY A GLASS PRISM > THE PHENOMENON OF SPLITTING OF WHITE LIGHT INTO ITS COMPONENT COLOURS WHEN IT PASSES THROUGH A PRISM. > VIBGYOR- SPECTRUM ~ ISAAAC NEWTON WA THE FIRST ONE TO USE GLASS PRISM TO OBTAIN THE SPECTRUM OF LIGHT CAUSE OF DISPERSION > LIGHT RAYS OF DIFFERENT COLOURS, TRAVEL WITH THE SAME SPEED IN VACUUM AND AIR BUT IN OTHER MEDIUM THEY TRAVEL WITH DIFFERENT SPEED AND BEND THROUGH DIFFERENT ANGLES, WHICH LEADS TO THE FORMATION OF SPECTRUM > RED LIGHT(MAXIMUM WAVELENGTH) AND VOILET(MINIMUM) ~ RED LIGHT TRAVELS FASTEST AND DEVIATES LEAS TWHILE VOILET LIGHT TRAVELS SLOWEST AND DEVIATES MAXIMUM RAINBOW + ANATURAL SPECTRUM APPEARING IN SKYAFTER RAIN > CAUSED BY DISPERSION OF SUNLIGHT BY TINY WATER DROPLETS, PRESENT IN ATMOSPHERE + DIRECTIONOPPOSITE TO. SUN + WATER DROPLETS AGT MIKE PRISM > /RED COLOURUPPER SIDE >| VOILETLOWER SIDE29| Page OPTICAL INSTRUMENT CAMERA > ALIGHT PROOF BOX CONSIST OF TWO ENDS. > ONE END-CONVERGING LENS > OTHER ENDLIGHT SENSITIVE FILM + IMAGE-REAL AND INVERTED > EXPOSURE TIME-TIME FOR WHICH LIGHT IS INCIDENT ON PHOTOGRAPHIC FILM MICROSCOPE > OPTICAL INSTRUMENT + FORMS A MAGNIFIED IMAGE OF SMALL NEARBY OBJEGT > INCRAESE THE VISUAL ANGLE SUBTENDED BYIMAGE AT THE EYE SO THAT THE OBJECT IS SEEN TO BE BIGGER AND DISTINGT TYPES OF MICROSCOPE, 1, SIMPLE MICROSCOPE 2. COMPOUND MICROSCOPE SIMPLE MICROSCOPE > USED FOR OBSERVING MAGNIFIED IMAGE OF OBJECTS + CONSISTOF A CONVERGING LENS OF SMALL FOCAL LENGTH + MAGNIFYING GLASS MAGNIFYING POWER + \ FINALIMAGE IF FORMEDATD, = m=142 + WHEN'FINALIMAGE AT INFINITE, — m30| Page COMPOUND MICROSCOPE > COMBINATION OF TWO LENS OBJECTIVE LENS- NEAR TO OBJECT. ll. EYEPIECE: FINAL IMAGE. MAGNIFYING POWER + FINALIMAGE ATD, mae (14 Uo= DISTANCE OF OBJECT FORMED OBJECTIVE LENS Vo= DISTANCE OF IMAGE FROM THE OBJECTIVE LENS, > FINALIMAGE AT INFINITE, TELESCOPES ~ TOLOQK AT DISTANT OBJECTS SUCH AS A STAR, A PLANET OR A DISTANT HILLS, ASTRONOMICAL TELESCOPE, + COMBINATION OF TWO LENS | OBJECTIVE LENS ll EYEPIECE LENS31] Page + USED FOR OBSERVING DISTINCT IMAGES OF HEAVENLY IMAGES BODY L.E., STAR MAGNIFYING POWER > FINALIMAGEIS FORMED ATD, > LENGTH OF TELESCOPE(L) = Fot Fe > WHEN FINAL IMAGE IS FORMED AT INFINITE + FOR LARGE MAGNIFYING POWER OF A TELESCOPE FoF objective lens eye piece lens distant object final image at infinity RESOLVING POWER > ABILITY OF THE"INSTRUMENT TO PRODUCE DISTINCTLY SPERATE IMAGES OF TWO-CLOSE OBJECTS > / THE MINIMUM DISTANCE B/W TWO OBJECTS WHICH CAN JUST BE SEEN AS SEPERATED BY THE OPTICAL INSTRUMENT IS LIMIT OF RESOLUTION OF THE INSTRUMENT > SMALLER THE LIMIT OF RESOLUTION, GREATER IS ITS RESOLVING POWER & VICE VERSA RESOLVING POWER OF A MICROSCOPE, > ITISDEFINE AS- THE RECIPROCAL OF THE DISTANCE B/W TWO OBJECTS WHICH CAN BE JUST RESOLVED WHEN SEEN THROUGH THE MICROSCOPE # RESOLVING POWER DEPENDS ON - | WAVELENGTH32| Page Il. REFRACTIVE INDEX OF THE MEDIUM B/W OBJECT AND THE OBJECTIVE Ill HALG ANGLE OF THE CONE OF LIGHT FROM ONE OF THE OBJECTS RESOLVING POWER OF A TELESCOPE + ITISDEFINED- THE RECIPROCAL OF THE SMALLEST ANGULAR SEPARATION B/W TWO DUSTANT OBJECT WHOSE IMAGE ARE SEEN SEPARATELY + RESOLVING POWER= 354 + ITDEPENDS ON- 1. WAVELENGTH I. DIAMETER OF THE OBJECT PERISCOPE, ~ ANINSTRUMENT FOR OBSERVATION OVER'AROUND OR THROUGH AN OBJECT, OBSTACLE OR CONDITION THAT PREVENTS DIRECT LINE OF SIGHT OBSERVATION FROM AN OBSERVER'S CURRENT-POSITION > ANGLE-45° USES OF PERISCOPE + USED IN SUBMARINE + ARMED VEHICLES INTERFERENCE OF LIGHT INTEREFERENCE > WHEN TWO LIGHT WAVES OF SIMILAR FREQUENCY HAVING A ZERO OR CONSTANT PHASE DIFFERENCE PROPOGATE IN A MEDIUM SIMULTANEOUSLY IN THE SAME DIRECTION, THEN DUE TO THEIR SUPERPOSITION MAXIMUM33| Page INTENSITY IS OBTAINED AT FEW POINT AND MINIMUM INTENSITY AT OTHER FEW POINTS, + REDISTRIBUTION OF ENERGY DUE TO SUPERPOSITION OF WAVES TYPES OF WAVES 1, CONSTRUCTIVE 2. DESTRUCTIVE QUESTION 1. WHEN THE KEROSINE OIL SPREAD ON WATER SURFACE SEEMS TO HAVE (A, DECENT COLOUR? 2. SOPA COLOUR HAS ALSO A BRILLIANT GQLOUR'IN THE SUNLIGHT? DIFFRACTION OF ‘LIGHT DIFFRACTION > BENDING OF LIGHT AROUND GORNORS AND SPREADING WITHIN THE GEOMATRICAL SHADOW OF OPAQUE OBSTACLES >» LIGHT DAVIATES FROMITS LINEAR PATH APPLICATIONS ~ | USED\IN DIFFRACTION GRATINGS ~ \ GRATING IS'USED SEPARATE COLOURS DIFFERENCE B/W INTERFERENCE AND DIFFRACTION + INTERFERENCE: SUPERPOSITION B/W THE WAVE COMING FROM TWO. COHERENT SOURCES 1.E., HAVING CONSTANT FREQUENCY & PHASE DIFFERENCE, > DIFFRACTION- SUPERPOSITION OF WAVES COMING FROM SINGLE OR ONE SOURCE,34| Page DOPPLER'S EFFECT > WHENEVER THERE IS A RELATIVE MOTION B/W A SOURCE AND A OBSERVER AND LIGHT, THE APPARENT FREQUENCY OF LIGHT RECEIVED BY OBSERVER IS DIFFERENT FROM THE TRUE FREQUENCY OF LIGHT EMITTED ACTUALLY FROM THE SOURCES ~ DELTAV CHANGE IN FREQUENCY 1, VE BLUE SHIFT 2. VE RED SHIFT USES 1, MEASURING THE SPEED OF STAR AND GALAXIES, 2. MEASURING THE SPEED OF SUN L.E., 2 KM/S 3. ESTIMATION OF VELOCITY OF AEROPLANES, ROCKETS, SUBMARINE ETC. POLARISATION THE PHENOMENON OF RESTRLTING OF ELECTRIC. VEGTORS OF LIGHT INTO A SINGLE DIRECTION USES 1. FOR NAVIGATION'IN SOLAR COMPASS IN POLAR REGIONS 2\ HOLOGRAPHY |.E., 3D MOTION PICTURE 3. USED IN OPTICAL STRESS ANALYSIS 4, LCD THROUGH POLARISATION OF LIGHT I.E., CALCULATOR, WATCHDIGITS35| Page REST- IF AN OBJECT DOES NOT CHANGE ITS POSITION WITH RESPECT TO ITS SURROUNDING WITH TIME, THE OBJECT IS SAID TO BE AT REST. MOTION- IF AN OBJECT CHANGES ITS POSITION WITH RESPECT TO ITS SURROUNDINGS WITH TIME, THEN THE OBJECT IS SAID TO BE IN MOTION. NOTE:- REST & MOTION ARE RELATIVE TERMS, |.E., AN OBJECT CAN BE IN REST AND ALSO IN MOTION AT THE SAME TIME WITH RESPECT TO DIFFERENT OBJECTSIN ITS SURROUNDING. TYPES OF MOTION ACCORDING TO THE NATURE OF THE MOVEMENT, MOTION IS CLASSIFIED INTO THREE TYPES AS FOLLOWS: A. LINEAR/RECTILINEAR/TRANSITORY MOTION ws IN LINEAR MOTION, THE OBJECT MOVES FROM ONE POINT TO ANOTHER IN EITHER A STRAIGHT LINE OR A CURVED PATH 3 THE LINEAR MOTION DEPENDING ON THE PATH OF MOTION IS FURTHER DIVIDED AS FOLLOWS |. RECTILINEAR MOTION — THE PATH OF THE MOTION IS A STRAIGHT LINE. ul. CURVILINEAR MOTION — THE PATH OF THE MOTION IS CURVED. EXAMPLES OF LINEAR MOTION ARE THE MOTION OF THE TRAIN, FOOTBALL, THE MOTION OF A CAR ON THE ROAD, ETC. B, ROTATORY/CIRCULAR MOTION ~% ROTATORY MOTION IS THE MOTION THAT OCCURS WHEN A BODY ROTATES ON ITS OWN AXIS. = EXAMPLES OF THE ROTATORY MOTION ARE AS FOLLOWS: © THE MOTION OF THE EARTH ABOUT ITS OWN AXIS AROUND THE, SUN IS AN EXAMPLE OF ROTARY MOTION WHILE DRIVING A CAR, THE MOTION OF WHEELS AND THE STEERING WHEEL ABOUT ITS OWN AXIS IS AN EXAMPLE OF ROTATORY MOTION cc. OSCILLATORY/ VIBRATORY MOTION % OSCILLATORY MOTION IS THE MOTION OF A BODY ABOUT ITS MEAN POSITION (BACK & FORTH), = EXAMPLES OF OSCILLATORY MOTION ARE36| Page WHEN A CHILD ON A SWING IS PUSHED, THE SWING MOVES TO AND. FRO ABOUT ITS MEAN POSITION. «| THE PENDULUM OF A CLOCK EXHIBITS OSCILLATORY MOTION AS IT MOVES TO AND FRO ABOUT ITS MEAN POSITION. * THE STRING OF THE GUITAR WHEN STRUMMED MOVES TO AND FRO BY ITS MEAN POSITION RESULTING IN AN OSCILLATORY MOTION. DISTANCE: THE LENGTH OF THE ACTUAL PATH TRAVELLED BY AN OBJECT DURING MOTION IN A GIVEN INTERVAL OF TIME IS CALLED THE DISTANCE COVERED BY THE OBJECT. = = = ~ IT DOES NOT DEPEND ON THE DIRECTION, LE., IT A SCALAR QUANTITY» SL UNIT: METER (M) DEVICE WHICH MEASURES DISTANCE- ODOMETER. IT CAN ONLY BE POSITIVE. SPEED: SPEED-THE DISTANCE TRAVELLED BY THE OBJECTPER UNIT TIME IS CALLED THE SPEED OF THE OBJECT. oe vw M. m. Distance Speed ITIS A VECTOR QUANTITY, LE., IT DEPENDS ON DIRECTION. Su. UNIT: ena = (5) VELOCITY = SPEED + DIRECTION OF\MOTION DIMENSIONAL FORMULA: M°L!T-F FOR A MOVING BODY VELOCITY GAN BE ZERO, NEGATIVE OR POSITIVE. Velocity < Speed , LE, MAGNITUDE OF VELOCITY IS EITHER EQUAL OR LESS THAN SPEED. ‘TYPES OF VELOCITY UNIFORM VELOCITY IF AN @BJECT UNDERGOES EQUAL DISPLACEMENT IN EQUAL INTERVAL OF TIMES, THEN IT\IS SAID TO BE MOVING WITH UNIFORM VELOCITY. NON-UNIFORM VELOCITY IFMAN OBJECT,UNDERGOES UNEQUAL DISPLACEMENT IN EQUAL INTERVALS OF TIME, THEN TT IS SAID TO BE MOVING WITH NON-UNIFORM OR VARIABLE VELOCTITY. AVERAGE VELOCITY THE RATIO OF THE TOTAL DISPLACEMENT TO THE TOTAL TIME TAKEN BY AN OBJECT IS CALLED THE AVERAGE VELOCITY OF THE OBJECT. Total Displacement Average velocity = Terai Time Taken INSTANTANEOUS VELOCITY38| Page THE VELOCITY OF ANY OBJECT AT ANY GIVEN INSTANT OF TIME IS CALLED INSTANTANEOUS VELOCITY. ar_dr Instantaneous Velocity = lim == ACCELERATION ACCELERATION: THE RATE OF CHANGE OF VELOCITY OF AN OBJECT IS CALLED ACCELERATION OF THE OBJECT. Change in Velocity Acceleration(a) = - a) Time Taken IISA VECTOR QUANTITY, LE, IT DEPENDS ON THE DIRECTION. S| UNIT- Meter per second square [4]. DIMENSIONAL FORMULA- M°LAT, ACCELERATION CAN BE ZERO, NEGATIVE & POSITIVE, IF VELOCITY OF ANY OBJECTS DECREASES ACCORDING TO TIME IT IS CALLED NEGATIVE ACCELERATION OR RETARDATION. ws IF VELOCITY OF ANY OBJECTS INCREASES AGCORDING TO TIME IT IS CALLED POSITIVE ACCELERATION. ts IF THERE IS NO CHANGE IN VELOCITY WITH TIME, THEN THERE IS NO ACCELERATION, L.E., ZERO ACCELERATION, vs IF VELOCITY IS ZERO IT DOES NOT MEANS THAT THE ACCELERATION IS ALSO ZERO. Gee HH TYPES OF ACCELERATION 1. UNIFORM ACCELERATION IF-VELQCITY OF, AN\OBJECT CHANGES EQUALLY IN EQUAL INTERVALS OF TIME THEN IT IS SAIDTO/MOVING WITH UNIFORM ACCELERATION. Il, NONUNIFORM ACCELERATION IF VELOGITY OF AN OBJECT CHANGES UNEQUALLY IN EQUAL INTERVALS OF TIMETHEN THE OBJECT IS SAID TO MOVING WITH NONUNIFORM ACCELERATION. i, AVERAGE ACCELERATION IF A BODY TRAVELS WITH UNIFORM ACCELERATION Ay & Ag IN TIME Ti & Ta RESPECTIVELY, THEN Average Acceleration = Total Change in Velocity Sree eee Iv. INSTANTANEOUS ACCELERATION ACCELERATION AT ANY INSTANT OF TIME IS CALLED INSTANTANEOUS: ACCELERATION.39| Page : av _ dv Instantaneous Acceleration = lim — abate dt ONE-DIMENSIONAL MOTION IT IS THE MOTION IN WHICH THE POSITION OF THE OBJECT CHANGES ONLY IN ONE DIRECTION. IN THIS CASE THE OBJECT MOVES ALONG A LINE. KNOWN AS: RECTILINEAR OR LINEAR MOTION. EXAMPLE- * MOTION OF TRAIN ALONG A STRAIGHT LINE, | MOTION OF FREELY FALLING OBJECTS. EQUATION OF ONE-DIMENSIONAL MOTION IF A BODY IS MOVING ALONG STRAIGHT LINE WITH A VELOCITY (U)AND AFTER SOME TIME T ITS VELOCITY CHANGES TO (V), IF UNIFORM ACCELERATION IS (A) AND THE DISTANCE TRAVELLED BY THE OBJECT IN TIME.) (S)\THEN FOLLOWING RELATION IS OBTAINED, WHICH ARE CALLED EQUATIONS OF MOTION. v=utat 1 Fut + pat? vu? +2as + IF AN OBJECT STARTS FROM REST, THEN U=0. IF AN OBJECT COMES AT REST. THEN V=0. > IF AN OBJECT MOVES WITH UNIFORM VELOCITY, THEN ITS ACCELERATION, A=O. + GRAPHS RELATED TO-ONE-DIMENSIONAL MOTION DISPLACEMENT-TIME GRAPH VELOCITY INCREASING | [VELOCITY INCREASING, CONSTANT veLociTy] | AT A CONSTANT ACCELERATION. INCREASING RATE AT A CONSTANT RATE £ g § a a a = . 3 3 3 3 * TIME t/s of TIME t/s os TIME t/s DISPLACEMENT —TIME DISPLACEMENT TIME DISPLACEMENT TINE GrarH FOR CONSTANT | | GRAPH FOR INCREASING | | GRAPH. FOR INCREASING VELOCITY veLocity ACCELERATION40| Page VELOCITY-TIME GRAPH un 1 ce Ss = > > = 3 = 5 o o a 2 o S - > = u=0 ° TIME ‘7s 7 TIME t/s ol TIME 7s VELOCITY—TIME VELOCITY—TIME VELOCITY=TIME GRAPH FOR CONSTANT| | GRAPH FOR INCREASING | | GRAPH FOR INCREASING VELOCITY VELOCITY ACCELERATION ACCELERATION-TIME GRAPH é z A é = £ i. 3 3 3 z z z é é é g & & é a é & & & 4 4 4 & 5 5 9 > 9G 9 > < of TIME t7s TIME t/s acd TIME */s ‘ACCELERATION-TIME ACCELERATION-TIME ACCELERATION-TIME GRAPH FOR CONSTANT | (®] GRAPH FOR INCREASING GRAPH FOR INCREASING VELOCITY VELOCITY ACCELERATION MOTION UNDER GRAVITY (FREE FALL) THE\OBJECT FALLING TOWARDS THE EARTH UNDER THE GRAVITATIONAL FORCE, ALONE IS GALLED A FREELY FALLING OBJECT AND SUC MOTION IS CALLED MOTION UNDER GRAVITY ORFREE FALL. EQUATION OF MOTION UNDER GRAVITY FOR UPWARD MOTION IF THE OBJECT IS THROWN UPWARD, EQUATION OF MOTION CAN BE WRITTEN AS: v=u-gt 1 h=ut-Sgt ut—59)41| Page FOR DOWNWARD MOTION IF THE OBJECT IS FALLING FREELY (U=0) UNDER GRAVITY, THEN EQUATION OF MOTION CAN BE WRITTEN AS: v=utgt heuttsgt? = utt+5g vi =u? +2gh TWO-DIMENSIONAL MOTION ITIS THE MOTION IN WHICH THE POSITION OF THE OBJECT CHANGES IN TWO DIRECTIONS. IN THIS CASE THE OBJECT MOVES ON A PLANE. FOR EXAMPLE — PROJECTILE MOTION & CIRCULAR MOTION. PROJECTILE MOTION WHEN THE OBJECT IS THROWN FROM HORIZONTAL MAKING AN ANGLE (8) EXCEPT 90°, THEN ITS MOTION UNDER GRAVITY IS ACURVED PARABOLIC PATH, CALLED TRAJECTORY AND ITS MOTION IS CALLED PROJECTILE MOTION. Range (R) B*42| Page CIRCULAR MOTION WHEN AN OBJECT MOVES IN A CIRCULAR PATH WITH A CONSTANT SPEED THEN THE MOTION OF THE OBJECT IS SAID TO BE IN A UNIFORM CIRCULAR MOTION. ‘TERMS RELATED TO UNIFORM CIRCULAR MOTION A. ANGULAR DISPLACEMENT(8) B. ANGULAR VELOCITY cc. ANGULAR ACCELERATION D. CENTRIPETAL ACCELERATION43| Page ANY ACTION WHICH CAUSES PUSH OR PULL ON AN OBJECT IS CALLED FORCE. ws S,], UNIT- NEWTON (N) 1 NEWTON= 1 KG MS" ~& CGS UNIT- DYNE 1 NEWTONS 10 DYNE ts MKS UNIT- KILOGRAM-METER PER SECOND-SQUARE. +s DIMENSION. [M1472] NEWTON'S LAW OF MOTION > PROPOUNDED BY S/R /SAAC NEWTONIN 1687. > BOOK-PRINCIPIA IEWTON'S FIRST LAW OF MOTION ACCORDING TO THIS LAW, AN OBJECT CONTINUOUS IN A'STATE OF REST OR INA STATE OF MOTION AT A CONSTANT SPEED ALONG A STRAIGHT LINE, UNLESS ANY NET EXTERNAL FORCE IS APPLIED ON IT. + THIS LAWIS ALSO KNOWN AS LAW OF INERTIA. NOTE:- A COMMON MISCONCEPTION ABOUT NEWTON'S FIRST LAW OF MOTION IS. THAT A FORCE IS REQUIRED TO KEEP AN'OBYECTIN MOTION. INERTIA THE PROPERTY OF AN OBJECT TO RESIST ANY CHANGES IN ITS STATES OF MOTION ALONG A STRAIGHT LINE.OR REST IS.CALLED INERTIA. TYPES OF INERTIA. i. / INERTIA OF MOTION. THE TENDENCY OF THE BODY TO CONTINUE IN ITS STATE, OF MOTION EVEN WHEN SOME UNBALANCED FORCE IS APPLIED ON IT IS CALLEDITHE INERTIA OF MOTION. EVERYDAY SCIENCE = WHEN A CARPET IS SUDDENLY JERKED THE DUSTS FLY OFF, BECAUSE DUE TO THE SUDDEN JERK THE CARPET MOVES BUT THE DUST ON ACCOUNT OF INERTIA OF REST IS LEFT BEHIND. %s THE PASSENGER STANDING IN A BUS TENDS TO FALL BACKWARDS WHEN THE BUS SUDDENLY STARTS, THIS IS BECAUSE HIS FEET ARE IN DIRECT CONTACT WITH THE FLOOR OF THE BUS AND THE FRICTION AT THE CONTACT |S HIGH THIS FRICTION DOES NOT ALLOW THE FEET TO SLIP ON THE FLOOR, THE FEET THEREFORE MOVE FORWARD WITH THE FLOOR AND THE UPPER PART OF THE.44| Page BODY'S STILL AT REST FOR A WHILE THUS THE PASSENGER GETS A BACKWARD JERK, ~s COIN DROPS INTO THE GLASS WHEN SUDDEN FORCE IS APPLIED ON THE CARDBOARD. IT IS BECAUSE OF THE PROPERTY OF INERTIA OF REST, THE COIN CONTINUES IN THE STATE OF REST. INERTIA OF REST: THE TENDENCY OF THE BODY TO CONTINUE IN STATE OF REST EVEN WHEN SOME EXTERNAL UNBALANCED FORCE IS APPLIED ON IT IS CALLED INERTIA OF REST. APPLICATIONS ° ITIS DANGEROUS TO JUMP OUT OF A MOVING VEHICLE (BUSTRAIN), THIS IS BECAUSE INSIDE THE TRAIN/BUS, COMPLETE BODY OF THE RASSENGER IS IN A STATE OF MOTION WITH THE TRAIN/BUS AND ON REAGHING THE GROUND HIS FEET COME TO REST BUT UPPER PART OF THE BODY. CONTINUES TO MOVE WITH THE SPEED OF VEHICLE AND THE PERSON FALLS FORWARD ON THE GROUND. HOWEVER IF IN CASE OF SOME EMERGENCY IF SOME PERSON WANTS TO JUMP SAFELY FROM A MOVING VEHIGEE HE SHOULD RUN FOR QUITE A WHILE IN THE DIRECTION OF MOTION OF THE VEHICLE AFTER THE JUMP SO THAT HIS ENTIRE BODY REMAINS IN MOTION FOR SOME TIME. t= WHEN A RUNNING CAR STOPS SUDDENLY, THE PASSENGER IS JERKED FORWARD. THE REASON IS THAT IN A RUNNING CAR, THE WHOLE BODY OF PASSENGER IS IN THE STATE OF MOTION. AS THE CAR STOPS SUDDENLY, THE LOWER PART OF HIS BODY BEING IN CONTACT WITH THE CAR COMES TO REST BUT HIS UPPER PART REMAINS IN THE STATE OF MOTION DUE TO THE INERTIA OF MOTION. THUS HE GETS JERKED FORWARD. INERTIA OF DIRECTION- THE TENDENCY OF AN OBJECT TO RESIST THE (CHANGE OF DIRECTION OF ITS MOTION EVEN WHEN SOME UNBALANCED FORCE IS\APPLIED ON IT IS CALLED INERTIA OF DIRECTION. INERTIA &MASS INERTIA IS THE NATURAL TENDENCY OF AN OBJECT TO REMAIN AT REST OR IN MOTION AT A CONSTANT SPEED ALONG A STRAIGHT LINE. THE MASS OF AN OBJECT ISA QUANTITATIVE MEASURE OF INERTIA. THE GREATER THE MASS, THE GREATER IS THE INERTIA OF BODY.45 | Page NEWTON'S SECOND LAW OF MOTION THE SECOND LAW OF MOTION STATES THAT THE RATE OF CHANGE OF MOMENTUM OF A BODY IS DIRECTLY PROPORTIONAL TO THE APPLIED UNBALANCED FORCE AND TAKES PLACE IN DIRECTION OF FORCE. ACCORDING TO 2° LAW, Change in momentum « Force me F= KEP KPOY_ Kma HERE, K= CONSTANT OF PROPORTIONALITY. > ITS VALUE IS ONE IN SI AND CGS SYSTEM. MOMENTUM THE MOMENTUM OF A MOVING BODY IS DEFINED AS THE PRODUCT OF ITS MASS AND VELOCITY. IF WE REPRESENT THE MASS AND VELOCITY OFA BODY BY MAND @ RESPECTIVELY, THEN MOMENTUM IS GIVEN BY mo °s THE DIRECTION OF MOMENTUM OF A BODY IS SAME AS THAT OF ITS VELOCITY. > THE SI UNIT OF MOMENTUM IS KILOGRAM METER-PER SECOND (KG M/S). LAW.OF. CONSERVATION.OF. MOMENTUM THE LAW OF CONSERVATION OF MOMENTUM STATES THAT THE MOMENTUM OF AN ISOLATED SYSTEM REMAINS CONSTANT UNLESS SOME NET EXTERNAL FORCE ACTS ONIT. + MOMENTUM CAN\NETHER\BE\NOT CREATED NOR BE DESTROYED IT CAN ONLY BE TRANSFERRED FROM ONE FORM TO ANOTHER. NEWTO! THIRD LAW OF MOTION IT STATES THAT TO EVERY ACTION THERE /S ALWAYS AN EQUAL AND OPPOSITE REACTION. APPLICATIONS % REGQILING OF A GUN: GUNS RECOIL WHEN FIRED, BECAUSE OF THE LAW OF CONSERVATION OF MOMENTUM. THE POSITIVE MOMENTUM GAINED BY THE BULLET IS EQUAL TO NEGATIVE RECOIL MOMENTUM OF THE GUN AND SO THE TOTAL MOMENTUM BEFORE AND AFTER THE FIRING OF THE GUN IS ZERO. = MOTOR CARS ARE ABLE TO MOVE ALONG A ROAD BECAUSE THE REACTION OF THE ROAD PUSHES THE CAR ALONG IN RESPONSE TO THE ACTION OF THE WHEELS PUSHING ON THE ROAD. SWIMMING IN A POND — A SWIMMER PUSHES (OR APPLIES FORCE) THE WATER WITH HIS HANDS AND FEET TO MOVE IN THE FORWARD DIRECTION IN WATER.45| Page ITIS THE REACTION TO THIS FORCE THAT PUSHES THE SWIMMER FORWARD. = PROPULSION OF AIRPLANE. THE PROPELLERS OF AN AIRPLANE PUSH THE AIR BACKWARDS AND THE FORWARD REACTION OF THE AIR MAKES THE AIRPLANE MOVE FORWARD. = PROPULSION OF JET AND ROCKETS: A ROCKET STANDING AT THE LAUNCHING. PAD HAS ZERO MOMENTUM. WHEN THE PROPELLANTS INSIDE THE ROCKET BURN, A HIGH VELOCITY BLAST OF HOT GASES IS PRODUCED. THESE GASES PASS OUT THROUGH THE TAIL NOZZLE OF THE ROCKET IN DOWNWARD DIRECTION WITH TREMENDOUS VELOCITY. THEREFORE THE ROCKET MOVES, UP WITH SUCH A VELOCITY SO AS TO MAKE THE MOMENTUM OF THE SYSTEM (ROCKET + EMITTED GASES) ZERO. FORCE: A FORCE IS THAT PHYSICAL QUANTITY WHICH TRIES TO. CHANGE OR (CHANGES THE STATE OF REST OR OF UNIFORMMOTION OF A BODY. TYPES OF FORCE THERE ARE TWO TYPES OF FORCE: 1. BALANCED FORCE: IF THERE ARE MANY FORCES-ACTING ON AN OBJECT BUT RESULTANT OF ALL OF THEM IS ZERO, THEN THE FORCES IS CALLED BALANCED FORCES. ONLY BRINGS A CHANGE IN THE SHAPE OF THE BODY. ll, UNBALANCED FORCE: IF THE RESULTANT OF ALL THE FORCES ACTING ON AN OBJECT IS NOT-ZERO, THEN THE FORCES IS CALLED UNBALANCED FORCE. CHANGE IN SPEEDOR\IN DIRECTION OF MOTION. BASIC FORCES IN NATURE. GRAYITATIONAL FORGE THE FORCE OF ATTRACTION BETWEEN ALL MASSES IN THE UNIVERSE IS CALLED THE GRAVITATIONAL FORCE. vs WEAKEST FORCE IN NATURE. %S\NEGLIGIBLE FOR LIGHT & SMALL BODIES. > SIGNIFICANT & CONSIDERABLE IN CELESTIAL BODY. WEAK NUCLEAR FORCE % DISCOVERED DURING STUDY OF decay. vs FORCE OF INTERACTION B/W ELEMENTARY PARTICLES. ws ITIS 10? TIMES’ STRONGER GRAVITATIONAL FORCE. ELECTROMAGNETIC FORCES47|Page THE ELECTROMAGNETIC FORCES ARE THE FORCES BETWEEN THE CHARGED. PARTICLES. WHEN CHARGES ARE AT REST, THEN THE FORCE IS CALLED AS ELECTROSTATIC FORCE. >s STRONGER THAN GRAVITATIONAL FORCE, ~%s IT DOMINATES ATOMIC AND MOLECULAR PHENOMENA. STRONG.NUCLEAR FORCES. THIS IS THE STRONGEST FORCE FOUND IN NATURE. THESE FORCES ACT BETWEEN THE PROTON AND THE NEUTRON IN ORDER TO BIND THEM IN THE NUCLEUS, > STRONGEST FORCE IN NATURE, %~ THIS FORCE IS 10°8 TIMES STRONGER THAN GRAVITATIONAL FORCES, 102 TIMES STRONGER THAN ELECTROSTATIC FORCES AND 10'S TIMES STRONGER THAN WEAK NUCLEAR FORCES. IMPULSE ALARGE FORCE WHICH ACTS ON AN OBJECT EORIAVERY SHORT INTERVAL OF TIME AND PRODUCES A LARGE CHANGE IN MOMENTUM JS'GALLED AN IMPULSIVE FORCE. Impulse (I) = Force x Time >s SIUNIT: NEWTON-SECOND (NS) > ITISAVECTOR QUANTITY. FRICTION FRICTION IS THE FORCE THAT OPPOSESTHE RELATIVE MOTION BETWEEN THE TWO OBJECTS WHEN ONE OBJECT ACTUALLY MOVES OR TRIES TO MOVE OVER THE SURFACE OF ANOTHER(OBJECT. ‘TYPES OF FRICTION THERE ARE THREE PES OF FRICTION: 1. STATIC FRICTION. IT IS AN OPPOSING FORCE THAT COMES IN INTO PLAY WHEN AN OBJECT TENDS/TO MOVE OVER THE SURFACE OF ANOTHER OBJECT. os SELF\ADJUSTING FORCE. \& INCREASES AS THE APPLIED FORCE INCREASES. Static Friction (f,) = usR WHERE, #t,= COEFFICIENT OF STATIC FRICTION & R= NORMAL. REACTION. 2. LIMITING FRICTION- THE MAXIMUM STATIC FRICTIONAL FORCE WHICH COME INTO PLAY WHEN THE OBJECTS JUST BEGINS TO SLIDE OVER THE SURFACE OF ANOTHER OBJECTS. Limiting Friction (f,) = mR WHERE, x= COEFFICIENT OF LIMITING FRICTION & R= NORMAL REACTION.48| Page > LIMITING FRICTION DOES NOT DEPEND ON AREA IN CONTACT BUT DEPENDS ON THEIR NATURE, 3. KINETIC FRICTION. THE OPPOSING FORCE WHICH ACTS WHEN OBJECT ACTUALLY MOVES OVER THE SURFACES IN CONTACT. Kinitic Friction (fy) = "48 WHERE, j= COEFFICIENT OF KINETIC FRICTION & R= NORMAL REACTION. 1. SLIDING FRICTION- WHEN ONE BODY SLIDES OVER THE SURFACE OF ANOTHER BODY, THE RESISTANCE TO ITS MOTION IS CALLED AS SLIDING FRICTION. IT IS ALWAYS MORE THAN ROLLING FRICTION. Il, ROLLING FRICTION: WHEN ONE BODY ROLLS OVER THE SURFACE'OF ANOTHER BODY, THE RESISTANCE TO ITS MOTION IS TERMED.AS, ROLLING FRICTION. FRICTION IN THIS CASE IS VERY SMALL. FRICTION: A NECESSARY EVIL, FRICTION IS NECESSARY FOR DOING VARIOUS'ACTIVITIES INOUR DAILY LIFE. + WE COULD NOT HOLD ARTICLES SUCH AS GLASS TUMBLER AND OTHER THINGS WITHOUT FRICTION. IT BECOMES VERY.DIFFICULT TO HOLD A GREASY GLASS. + WE COULD NOT WRITE WITH PEN OR PENCIL IF THERE IS NO FRICTION. + FRICTION HELPS OBJECTS TO MOVE, STOP ORO CHANGE THE DIRECTION OF MOTION. WE CANNOT WALK WITHOUT FRICTION. FRICTION IS AN EVIL + IT CAUSES WEAR AND TEAR. FOR EXAMPLE, SOLES OF SHOES, BALL BEARINGS, STEPS OF A STAIR, PARTS OF MACHINES ETC. + FRICTION'PRODUCES HEAT) WHEN A MACHINE IS OPERATED, HEAT GENERATED CAUSES DAMAGE T@ THE MACHINERY. METHODS OF REDUCING FRICTION > / BY POLISHING. + | USINGLUBRICANTS. ~> \ USING BALL BEARING.49] Page ELECTRIC CURRENT > WHEN AN ELECTRIC CHARGE FLOWS THROUGH A CONDUCTOR, THEN THERE IS AN ELECTRIC CURRENT IN THE CONDUCTOR > INATORCH, THE CELLS PROVIDE FLOW OF CHARGES OR AN ELECTRIC CURRENT THROUGH THE TORCH BULB TO GROW. —> Current (I) — electron (e") > ELECTRIC CURRENT IS DEFINED AS THE RATE OF FLOW OF CHARGE THROUGH ACONDUCTOR. IF Q AMOUNT OF CHARGE FLOWS THROUGH A CONDUCTOR IN TIME T, THEN > SIUNIT-AMPERE) SCALER QUANTITY > \ WHEN 1,.C CHARGE FLOWS THROUGH ANY CROSS SECTION OF A CONDUCTOR IN NSEC THEN THE ELECTRIC CURRENT FLOWING THROUGH IT IS SAID TO BE 1 AMPERE. > SMALLUNIT 1MA= 102A 1UA= 108A + DIRECTION OF ELECTRIC CURRENT ~ DIRECTION OF FLOW OF POSITIVE CHARGES IS TAKEN TO BE THE DIRECTION OF ELECTRIC CURRENT. > CONVENTIONALLY THE DIRECTION OF ELECTRIC CURRENT /S TAKEN AS OPPOSITE TO THE DIRECTION OF THE FLOW OF ELCTRONS:50| Page ELECTRICITY V/S ELECTROSTATICS > ELECTRICITY DELALS WITH MOVING CHARGE (FLOW OF CHARGE) > ELECTROSTATICS DEALS WITH THE STATIONARY CHARGES: TYPES OF ELECTRIC CURRENT 1, DC(DIRECT CURRENT) WHOSE MAGNITUDE AND DIRECTION DO NOT CHANGE WITH TIME EXAMPLE: A CELL, BATTERY OR DC DYNAMO 2. AC (ALTERNATING CURRENT) WHOSE MAGNITUDE CHANGES CONTINUOUSLY AND DIRECTION CHANGES PERIODICALLY EXAMPLE: AC DYNAMO. Current + Current Time . Time Allernating Current Direct Curent CURRENT DENSITY > CURRENT DENSITY AT A POINT INA CONDUCTOR IS DEFINED AS THE AMOUNT OF CURRENT FLOWING THROUGH PER UNIT AREA OF CROSS-SECTION OF THE CONDUGITOR PROVIDED THE AREA IS HELD IN A DIRECTION NORMAL TO THE CURRENT ]=ELECTRIC CURRENT/AREA OF CROSS SECTION >) SIUNTT:A/M2 ‘Flow of current A ' J= The flow of current over Cross SectionS1| Page ELECTRICAL POTENTIAL AND POTENTIAL DIFFERENCE + ELECTRON ALWAYS FLOWS FROM A REGION WHERE THEIR DENSITY IS HIGH TO REGION WHERE THEIR DENSITY IS LOW > CONVENTIONALLY POSITIVE TERIMANL OF A CELL OR BATTERY IS AT HIGHER POTENTIAL THAN ITS NEGATIVE TERMINAL. + ELECTRON-NEGATIVE TO POSITIVE TERMINAL > ELECTRIC CURRENT: POSITIVE TO NEGATIVE TERMINAL ELECTRIC POTENTIA\ > THE ELECTRIC POTENTIAL OF A POINT IS DEFINED AS THE AMOUNTOF WORK DONE BY EXTERNAL FORCE WHEN A UNIT CHARGE MOVES FROM INFINITY TO. THAT POINT IN THE ELECTRIC FIELD Electric Potential Energy + Electric potential energy are similar to gravitational potential energy ~ both involve field forces. Gravitational potential = @ mm @ reson vewecn masses It depends on the mass and Woke Wer the field strength and the tom! _ relative position — @ PE, =mgAh Tania clocks pobeelial © din Pe aonet energy is a result of ig interaction between Work done by Work done by charges. Itdepends on the} electric field ecernaltere! charge and field strength TREE and relative position. ; tow PE FFF EPPS ETS ELECTRIC POTENTIAL DIFFERENCE ~ \THE\DIFFERENCE OF POTENTIALS OF TWO POINTS IN THE ELECTRIC FIELD > — SIUNIT- VOLTAV) — SCALER QUANTITY > LETWBE THE WORK DONE IN MOVING A CHARGE Q FROM POINT B TO POINT A, THEN THE POTENTIAL DIFFERENCE(Vs~V) IS EQAUL TO W/Q, w Ya-Van ae52| Page > THE ELECTRIC POTENTIAL DIFFERENCE B/W TWO POINTS IS SAID TO BE 1 VOLT IF / JOULE WORK IS DONE IN MOVING 1 COULOMB OF ELECTRIC CHARGE FROM ONE POINT TO OTHER. avoir - JOULE ~ 1COULOMB > O9V 1UV=108VIKV= 103V. IMV= 108V VOLTMETER > DEVICE USED TO MEASURE ELECTRIC POTENTIAL DIFFERENCE 8/W TWO POINTS IN A CIRCUIT > HIGH RESISTANCE DEVICE > CONNECTED IN PARALLEL OHM’S LAW + GIVEN BY GEORG SIMON OHM IN 1827 + GIVES A RELATIONSHIP B/W CURRENT AND POTENTIAL DIFFERENCE ~ ACCORDING TO THIS LAW, THE LECTRIC CURRENT FLOWING THROUGH A CONDUCTOR IS DIRECTLY PROPORTIONAL TO THE POTENTIAL DIFFERNCE APPLIED ACROOS IT ENDS, PROVIDED THE PHYSICAL CONDITIONTEMP) REMAINS UNCHANGED V=IR + WHERE) RIS THE CONSTANT OF 'PROPORTIONALITY, CALLED RESISTANCE OF THE CURRENT AT A GIVEN TEMPERATURE EVERYDAY SCIENCE WHY THELIGHTS OF A CAR ARE DIMMED WHEN STARTER IS OPERATED? > \ASIT DRAWS MORE CURRENT FROM THE BATTERY FOR THE OPERATION OF AR. THEREFORE THE VOLTAGE ACROSS THE LIGHT BULB IS LOWERED, HENCE THE LIGHTS OF CAR IS DIMMED RESISTANCE + PROPERTY OF A CONDUCTOR BY VIRTUE OF WHICH IT OPPOSSES/ RESISTS FLOW OF CHARGESIN IT > ITARISES DUE TO THE MUTUAL COLLISIONS OF ELECTRONS WHICH DRIFT THROUGH THE CONDUCTOR53| Page > SIUNIT-OHM > SCALER QUANTITY + RESISTANCE OF A CONDUCTORS SAID TO BE 1 OHM, IF A POTENTIAL OF 1 VOLT ACROSS THE ENDS OF THE CONDUCTOR MAKES A CURRENT OF 1 AMPERE TO FLOW THROUGH IT 1 Volt 1 Ohm = Tampere BESISTOR + ACOMPONENT IN AN ELECTRIC CIRCUIT WHICH ‘OFFERS RESISTANCE TO THE FLOW OF ELECTRONS CONSTITUTING ELECTRIG, CURRENT + RESISTORS ARE USED TO MAKE THOSE DEVICESIWHERE HIGH RESISTANCES IS REQUIRED + ITREDUCES CURRENT IN A CIRCUIT E.G., ALLOYS LIKE NICHROME, MANGANIN AND CONSTANTAN RESISTIVITY > RESISTIVITY OF A CONDUCTORS DEFINED A THE RESISTANCE OF A CONDUCTOR OF UNIT LENGTH AND UNIT CROSS SECTIONAL AREA > SIUNIT-OAMMETER + THE RESISTWiTy Of A MATERIAL-DOES NOT DEPEND ON ITS LENGTH OR THICKNESS SUT)DEPENDS ON THE NATURE OF THE SUSBATNACES: | ITISA GHARACTERISTIC PROPERTY OF THE MATERIAL OF CONDUCTOR AND VARIES ONLY IF ITS TEMPERATURE CHANGES + INSULATORS SUCH AS GLASS, RUBBER, EBONITE HAVE A VERY HIGH RESISTIVITY WHILE CONDUCTORS HAVE LOW RESISTIVITY + ALLOYS HAVE HIGHER RESISTIVITY THAN THAT OF THEIR CONSTITUENT METALS + ALLOYS ARE USED TO MAKE HEATING ELEMENTS OF DEVICES SUCH AS ELECTRIC IRON, HEATERS THIS IS BECAUSE THEY DO NO OXIDISE EASILY AT HIGH TEMPERATURE54| Page + THE HIGH RESISTIVITY OF ALLOYS ALLOWS DISSIPATION OF ELECTRICAL ENERGY IN THE FORM OF HEAT FACTORS ON WHICH THE RESISTANCE OF A CONDUCTOR DEPENDS |. LENGTH OF THE CONDUCTOR- I. AREA OF CROSS SECTION OF THE CONDUCTOR ul, NATURE OF THE MATERIAL OF THE CONDUCTOR 1. ON TEMPERATURE ¥ RESISTANCE OF A CONDUCTOR INCREASES LINEARLY WITH INCREASING TEMPERATURE ¥ SEMICONDUCTOR: DECREASE WITH INCREASE TEMPERATURE ¥_ ELECTROLYTESDECREASE WITH INCREASE IN TEMPERATURE ¥ ALLOY: INCREASE WITH INCREASE IN TEMPERATURE (WEAK DEPENDENCE) COMBINATION OF RESISTANCE, > COMBINATION OF RESISTOR IS REQUIRED TO ACHIEVE THE DESIRED VALUE OF RESISTANCE IN A PARTICULAR CIRCUIT 1, SERIES COMBINATION 2. PARALLEL COMBINATION, SERIES COMBINATION > / WHEN TWO ORMORE RESISTORS ARE CONNECTED END TO END > MAXIMUM EFFECTIVE RESISTANCE > \\IN SERIES'COMBINATION, = CURRENT: SAME ~ POTENTIAL (V)- DIFFERENT > RSRi+RetRot + THIS PROVES THAT OVERALL RESISTANCE INCREASES WHEN RESISTORS ARE, CONNECTED IN SERIES IN SERII MBINATI + CURRENT IN CIRCUIT IS INDEPENDENT OF THE RELATIVE POSITION OF VARIOUS RESISTORS.55| Page + VACROSS ANY RESISTOR IS DIRECTLY PROPORTIONAL TO THE RESISTANCE OF THAT RESISTOR, IF THE CURRENT THROUGH THE CIRCUIT IS CONSTANT > VE ViE Vet V5 > R>R:,Re, Ra, PARALLEL COMBINATION OF RESISTORS > WHEN RESISTORS ARE CONNECTED IN PARALLEL TO EACH OTHER fd Req Rr Ra Rs IN PARALLEL COMBINATION + THE CURRENT THROUGH EACH RESISTOR IS INVERSELY PROPORTIONAL TO THE RESISTANCE > VOLTAGE: INDEPENDENT > Ieht tls + TOTAL RESISTANCE IS LESS THAN THE LEAST RESISTANCE OF THE CIRCUIT > Req THE RESCIPROCAL OF RESISTANCE,56| Page > SIUNIT-OHM" OR MHO OR SIEMEN + SCALER QUANTITY + CONDUCTANCE = 1/RESISTANNCE CONDUCTIVITY > RECIPROCAL OF RESISTIVITY > SIUNIT-OHM'M" OR MHO M" OR SIEMEN M7 > CONDUCTIVITY = 1/ RESISTIVITY NOTES > CONDUCTIVITY OF CONDUCTOR INCREASES WITH INCREASE IN TEMPERATURE + CONDUCTIVITY OF SEMICONDUCTOR INCREASES WITH INCREASE IN TEMPERATURE > INSULATORS— NO EFFECT ~ THE CONDUCTIVITY OF METALS AND ALLOYS\INCREASES AS THEY ARE COOLED — THE PRODUCT OF CONDUCTIVITY AND RESISTIVITY AND CONDUCTANCE AND RESISTANCE FOR A MATERIAL IS|ALWAYS UNITY CLASSIFICATION OF MATERIALS IN TERMS OF CONDUCTIVITY %s CONDUCTORS-SILVER, ALUMINIUM = INSULATORS. GLASS, RUBBER > SEMICONDUCTORS. GERMANIUM, SILICON SUPERCONDUCTORS — \ SUPERCONDUCTORS- WHEN FEW METALS ARE COOLED THEN BELOW A GERTAIN CRITICAL TEMPERATURE THEIR ELECTRICAL RESISTANCE SUDDENLY BECOMES ZERO. IN THIS STATE. THESE SUBSTANCES ARE CALLED SUPERCONDUCTORS AND THIS PHENOMENON IS CALLED SUPERCONDUCTIVITY. > MERCURY BECOMES SUPERCONDUCTOR AT 4.2K, LEAD AT 7.25 K AND NIOBIUM AT 9.2 K THERMISTORS + AHEAT SENSITIVE DEVICE WHOSE RESISTIVITY CHANGES VERY RAPIDLY WITH (CHANGE OF TEMPERATUREs7|Page # USES 1. TO DETECT SMALL TEMP CHANGES AND TO MEASURE VERY LOW TEMP I. TO SFAEGUARD THE FILAMENT OF THE PICTURE TUBE OF A TELIVISION SET AGAINST THE VARIATION OF CURRENT i. INTEMP CONTROLS UNITS OF INDUSTRY Iv. IN PROTECTION OF WINDINGS OF GENERATORS, TRANSFORMER AND. MOTROS Semiconductor vs Superconductor ee a ten! Bg Sree Mae ere Sai Oa D TL) v rection Ree any Reve saa ome a Cree acs NCUA aed oc) oteotar Maced CLUDE Malls aa? cay ae ia) eels ic ELECTRICAL CELL, > | ASOURCE OF\EMF WHICH MAINTAINS THE CONSTANT FLOW OF CURRENT ACROSS (AN ELECTRIC CIRCUIT # EMF OF A CELL, MAXIUMUN POTENTIAL DIFFERENCE B/W TWO ELECTRODES OF THE-GEUL WHEN NO CURRENT IS DRAWN FROM THE CELL # INTERNAL RESISTANCE OF A CELL: RESISTANCE OFFERED BY THE ELECTROLYTE AND ELECTRODES OF A CELL WHEN THE ELECTRIC CURRENT FLOWS THROUGH IT58| Page HEATING EFFECTS OF ELECTRIC CURRENT INTRO > WHEN AN ELECTRIC CURRENT IS PASSED THROUGH A HIGH RESISTANCE WIRE, LIKE NICHROME WIRE, THE RESISTANCE WIRE BECOMSE VERY HOT AND PRODUCES HEAT + EXAMPLE: AN ELECTRIC FAN BECOMES WARM IF USED CONTINUOSLY FOR LONGER TIMES JOULE’S LAW OF HEATING > WHEN AN ELECTRIC CURRENT PASSES THROUGH A CONDUCTOR'FOR SOME TIME, THE CONDUCTOR GETS HEATED UP. > THUS HEATING OF A CONDUCTOR DUE TO THE FLOW OF ELECTRIC CURRENT THROUGH IT IS KNOWN AS JOULE'S LAW:OF HEATING. HEAT GENERATED, H=PRt # — JOULE'S LAW STATES THAT H (HEAT) = I (CURRENT) X V (VOLTAGE) XT (TIME THE CURRENT IS ALLOWED TO FLOW). # OR, WRITTEN DIFFERENTLY, H (HEAT) = I? (CURRENT SQUARED) X R (RESISTANCE) XT (TIME THE CURRENT IS ALLOWED TO FLOW). # — JOULE'S LAW IS AN EQUATION THAT GIVES THE AMOUNT OF HEAT (ENERGY) DELIVERED TO SOMETHING. 4 JOULE’S LAW STATES THE AMOUNT OF HEAT PRODUCTION IN A CONDUCTORIS: 1. DIRECTLY PROPORTIONAL TO THE SQUARE OF ELECTRIC CURRENT FLOWING THROUGH IT. \. IS DIRECTLY PROPORTIONAL TO THE RESISTANCE OF THE CONDUCTOR. i, DIRECTLY PROPORTIONAL TO THE TIME FOR WHICH ELECTRIC. CURRENT FLOWS THROUGH THE CONDUCTOR.59| Page USES OF HEATING EFFECTS OF ELECTRIC CURRENT 4 The heating effect of electric current is used in electrical appliances like electric heater, electric iron, electric room heater, immersion heater elec- tric kettle, hair dryer etc. All these appliances have a coil of wire called an element. When electric. current flows through the element it becomes hot and gives out heat. The amount of heat produced in a wire depends upon its material, length and thickness. eectric Hears, electric tron oot” ROOM Hoon a—_ ELECTRIC BULB — BULB HAS A FILAMENT MADE OF TUNGSTEN — TUNGSTEN HAS AHIGH RESISTIVITY AND A HIGH M.P.3380°C —> MOST OF THE POWER CONSUMED BY THIS, IS DISSIPATED IN THE FORM OF HEAT AND SOME PART IS CONVERTED INTO LIGHT > THE FILAMENT IS THERMALLY ISOLATED AND THE BULB IS FILLED WITH INACTIVE NITROGEN OR ARGONGAS TO PROLONG THE LIFE OF FILAMENT EVERYDAY SCIENCE, ~ / BULBS FUSE SOMETIMES WHEN THEY ARE SWITCHED ON AS THE BULB IS. SWITCHED ON-ITS LIGHT UP AND ITS TEMPERATURE INCREASES, > \\DUB.TO WHICH THE STRENGTH OF THE FILAMENT OF THE BULB DECREASES. AETERMANY CYCLES, THE STRENGTH OF THE BULBS BECOMES VERY LOW, WHEN SUCHAS BULBED IS SWITCHED ON, ITS FILAMENT BURNS OFF + THE BRIGHTNESS OF LIGHT BULBS DECREASE GRADUALLY WITH ITS PERIOD OF USE BECAUSE > WHEN THE BULB IS USED, THE EVAPORATION OF THE METAL FROM THE, FILAMENT OF BULB TAKES PLACE WITH TIME WHICH DEPOSITS ON THE INNER SIDE OF THE GLASS WALL AS BLACK SUBSTANCES. DUE TO THIS THE FILAMENT OF THE BULB BECOMES THINNER AND THINNER WITH USE , THIS IN60| Page TURN THE INCREASE THE RESISTANCE OF THE BULB SO BRIGHTNESS OF BULB. DECRAESES GRADUALLY WITH ITS PERIOD OF TIME ELECTRIC FUSE ~ USED AS SAFETY DEVICE IN HOUSEHOLD CIRCUITSBASED ON HEATING EFFECT OF CURRENT ~ CONNECTED IN SERIES WITH THE MAIN SUPPLY > FUSE CONSISTS OF ALLOY OF LEAD AND TIN WHICH HAS APPROPRIATE MEALTING POINT. > WHEN THE CURRENT FLOWING THROUGH THE CIRCUIT EXCEEDS THE'SAFE, LIMIT THE TEMPERATURE OF THE FUSE WIRE INCREASE DUEFO WHICH FUSE WIRE MELTS AND BREAKS THE CIRCUIT > THIS HELPS TO PROTECT THE OTHER CIRCUIT ELEMENTS FROM HAZARDS CAUSED BY THE HEAVY CURRENT. POWER > AMOUNT OF ELECTRIC ENERGY CONSUMED IN A CIRCUIT PER UNIT TIME > SIUNIT-WATT OR JOULE/SEC + ELECTRIC POWERIS SAID TOBE 1\ WATT IF 1 AMO CURRENT FLOWS THROUGH ACIRCUIT HAVING 1 VOLT POTENTIAL DIFFERENCE > 1 WATT# 1 VOLT*1 AMR BIGGER UNITS OF POWER > (1 KW= To3W. >\ 1 MW= ‘Loew > ‘\GWa199w > PRACTIGAEUNIT: 1HP= 746W ~ COMMERCIAL UNIT- 1KWH= 1000WH = 1000"3600WS = 3.6°106WS = 3.6"106) NUMBER OF UNITS CONSUMED BY ELECTRICAL APPLIANCES > NO OF UNITS= WATT*HOURS'DAY/ 1000