SECTION A

ACTIVITY-A 1
AIM OF THE ACTIVITY
To Measure the resistance and impedance of an inductor and with or without
iron core.
Apparatus required
A battery, a high resistance rheostat, D.C ammeter, D.C voltmeter, one way key,
variable A.C source (variac), A.C ammeter, A.C voltmeter, connecting wires.
THEORY AND PROCEDURE

1)A high resistance and large number of turns coil wrapped on a hollow
cylindrical asbestos core, a soft iron rod fitting into the asbestos core.
2) The impedance was measured without iron core by using Ohm’s law. The
variac was connected to A.C mains, A.C ammeter, and A.C voltmeter used to
measure A.C current and voltage.
3) As the circuit obey Ohm’s law, the ratio of the voltmeter reading to the
corresponding ammeter reading will give the impedance of the inductor
without iron core.
4) Then the iron core was inserted inside the hollow cylindrical asbestos core of
the inductor.
CONCLUSION
1)The resistance of the inductor coil is bout same with and without soft iron
core in flow of D.C
2) Impedance of inductor with iron core is much higher than without it​
ACTIVITY-A 2
AIM OF THE ACTIVITY
To assemble a household circuit comprising three bulbs, three(ON/OFF)
switches, a fuse and a power source.
MATERIAL REQUIRED​
​
Three bulbs (6 V, 1W) each, fuse of 0.6 A, main switch a power supply (battery.
eliminator), three (on/off) switches flexible connecting wire with red and black
plastic covering, a fuse wire. Main electric board with a two-pin socket and
main switch.

THEORY AND PROCEDURE

1)AVO meter or Multimeter is a single measuring device acting as ammeter, a
voltmeter and an ohmmeter. It can measure alternating current (voltage)as
well as direct current (voltage) in addition to resistance.

2) For this purpose, its panel is divided into five different sections. There are
many ranges in each section so that it can measure from micro to mega units.
Rotation of knob changes the section and the range in one section.

3) To measure the resistance, turn the micro-meter knob to ohmmeter range of

middle value. Touch the two lead points with ach other and adjust the pointer
to zero reding on resistance scale. Now touch the two leads with the two ends
of the resistor whose resistance is to be measured. The position of the pointer
on ohmmeter scale gives value of the resistance.

4) To measure the voltage, turn the multimeter knob to voltage range. Touch
the two leads with the two points between which the voltages is to be
measured. The position of the pointer on the scale gives the value of the
voltage.

5) To measure the current, turn the multimeter knob to A.C current range

6) To check the continuity of a circuit, turn the multimeter knob to ohmmeter

range of least value. Touch the two leads with the two points and adjust the
pointer to zero reading on resistance scale. This zero lies on the extreme right
of the multimeter scale.

Now touch the two leads with the two points, one with each point between
which continuity is to tested. If the multimeter pointer gives zero value of the
resistance, the two points under test have continuity. In case of a loose contact
the pointer will not come to zero and read some resistance value. If there is
some break in between the points, the pointer will not move at all. It will stay
at extreme left of a multimeter scale which corresponds to infinite resistance.

CONCLUSION

The bulb glows when the switch is ON. It stops glowing when the switch is put
OFF.
 ACTIVITY-A 3

AIM OF THE ACTIVITY

To study the variation in potential drop with length of a wire for a steady
current.

MATERIAL REQUIRED​
potentiometer, A fully charged 2.2 V battery or battery eliminator, a low
resistant rheostat, a voltmeter of range (0-2V), an ammeter, a one way key, a
jockey, a set square, connecting wires and a piece of sand paper.

THEORY AND PROCEDURE

1)Draw a circuit diagram showing the scheme of connections as in figure.

2)Remove the insulation from the ends of the connecting copper wires with a
sand paper.
3)Connect the positive pole of the battery (eliminator) (a battery of constant
e.m.f.) to the zero end (P) of the potentiometer and the negative pole through
a one-way key, an ammeter and a low resistance rheostat to the other end (Q)
of the potentiometer.
4)Connect the positive terminal of the voltmeter to the end P of the
potentiometer and the negative terminal to the jockey.
5)Touch the end of the jockey to the end Q of the potentiometer.
6)Close the key and set the rheostat such that the voltmeter gives full scale
deflection (3 V).
7)Touch the jockey at end P at 0 (zero) cm. The voltmeter will give zero
deflection.
8)Touch the jockey at marks separated by 50 cm length of wire. Note the
voltmeter reading in each case.
8)Record your observations in tabular form as given ahead.
OBSERVATION

sl length of Voltmeter 𝑉
𝐾= 𝑙
𝑖𝑛 𝑉/𝑐𝑚
no potentiometer reading in
wire in cm volt

1 50 0.4 0.008

2 100 0.8 0.008

3 150 1.2 0.008

4 200 1.6 0.008

5 300 2.4 0.008

RESULT
𝑉
The ratio 𝑙
remains constant and known as potential gradient of the wire.

ACTIVITY-A 4

AIM OF THE ACTIVITY

To draw the diagram of a given open circuit comprising at least a battery,
resistor, rheostat, key, ammeter and voltmeter.
MATERIAL REQUIRED​
battery, one way key, constantan coil rheostat, ammeter ,voltmeter and
connecting wire
THEORY AND PROCEDURE

Mark the Components that are not Connected in Proper Order and Correct the
Circuit and Also the Circuit Diagram. An open circuit is the combination of
primary components of electric circuit in a such a manner that on closing the
circuit no current is drawn from the battery.

​
Procedure​
Ammeter: It should be connected in series, with the battery eliminator.​
Voltmeter: It should be connected in parallel to the resistor.​
Rheostat: It should be connected in series (in place of resistance coil) with the
battery eliminator.​
Resistance coil: It should be connected in parallel (in place of rheostat).​
One way key: It should be connected in series to the battery eliminator.​
Correct circuit diagram: (Components connected in proper order)

SECTION B
ACTIVITY-B 1
AIM OF THE ACTIVITY
To observe the refraction and lateral deviation of a beam of light incident
obliquely on a glass slab.
MATERIAL REQUIRED​
glass slab, drawing board, white paper sheet, drawing pins, protactor
THEORY AND PROCEDURE
1)When a ray of light becomes incident on a parallel faced glass slab, it
emerges from it in same direction as the incident ray. It only suffers a lateral
displacement, proportional to the slab thickness.
The lateral displacement is given by
𝑑 = t sec r sin (i-r)
2)The glass slab was placed in the middle of the paper on the drawing board.
3) As shown in the diagram the incident ray and normal at that point were
drawn by the help of protactor
4) The board pins were fixed on the incident line and as per the image shown in
the opposite side the emergent ray was drawn. Mark the perpendicular line on
the incident ray from the emergent ray as shown in the diagram.
CONCLUSION

1)The angle of incidence is equal with the angle of emergence

2) The lateral displacement increases with the increase of the thickness of the
slab
3) The lateral displacement increases with the angle of incidence
ACTIVITY-B 2
AIM OF THE ACTIVITY
To observe polarization of light using two polaroids.
MATERIAL REQUIRED
Thin glass sheet, a source of monochromatic light beam with parallel rays, a
polaroid
THEORY AND PROCEDURE
1)When an unpolarised light was made to incident on a thin glass sheet at
angle of 57.5 ° the reflected and refracted rays depart from each other at an
angle of 90°
2)The reflected ray was completely plane polarised and the refracted ray was
partly plane polarised. It can be tested by polaroid.
3) The thin glass sheet was kept in a horizontal plane surface with a hole under
the sheet. A beam of monochromatic light beam with parallel rays was made to
incident on the upper surface of the glass sheet.
4) The angle of incidence was adjusted to 57.5 ° . It was observed that the
reflected ray and the refracted ray were perpendicular to each other.
5) A polaroid was placed between incident light and our eyes. It as rotated
about an axis along incident ray. It was observed that there is no change in
intensity of light, means light was unpolarized.
6) Then the polaroid was rotated between refracted light and our eyes, the
intensity of light became maximum and minimum with the rotation of the
polaroid about 90°, means refracted light was partly plane polarized.
7) Then the polaroid was rotated between reflected light and our eyes, the
intensity of light became maximum and zero with the rotation of the polaroid
about 90°, means reflected light was completely plane polarized.
ACTIVITY-B 3
AIM OF THE ACTIVITY
To study the nature and size of the image formed by a convex lens on a screen
by using a candle and a screen for different distances of the candle from the
lens.
MATERIAL REQUIRED
An optical bench with three uprights, a convex lens, a burning candle, a
card-board screen
THEORY AND PROCEDURE

1)As per thin lens formula,

1 1 1
𝑓
= 𝑣
− 𝑢

𝑢 = ∞⟹𝑣 = 𝑓, 𝑢 =− 2𝑓⟹𝑣 = 2𝑓, 𝑢 =− 𝑓⟹𝑣 = ∞

2)Find rough focal length of the convex lens by usual method.​
3) Mount the convex lens in holder in central upright and keep it in the middle
of the optical bench.​
Mount the card-board screen on another upright and keep it at distance equal
to rough focal length of the lens, from the central upright.​
Mount the burning candle in third upright and keep it on the other side of the
central upright and near the end of the optical bench.​
4) Adjust heights so that the inverted image of erect flame of burning candle is
formed on screen. Move the screen to make the image sharp. The screen will
be nearly at the focus of the convex lens. The image will be real inverted and
much more diminished.
5) As the burning candle is moved towards the lens on one side, the screen has
to be moved away from the lens on other side, for getting sharp flame image.
The inverted image size increases.​
6) When the position of the candle is at distance 2f from the lens, the screen is
also at same distance on the other side. The image size will be equal to the
actual flame size.​
7) Move the candle further nearer to the lens. The screen has to be moved
away for getting an enlarged inverted real image on screen.​
As the candle reaches the focus of the lens, the screen may not be able to get
its image which will be at infinity i.e. beyond the ends of the optical bench.

Conclusion​
This change in position, nature and size of the image is according to theoretical
predictions.
ACTIVITY-B 4
AIM OF THE ACTIVITY
To obtain a lens combination with the specified focal length by using two lenses
from the given set of lenses.
MATERIAL REQUIRED
A set of convex lenses, lens holder with stand, a white painted vertical wooden
board with board stand half metre scale.
THEORY AND PROCEDURE
1)The reciprocal of focal length in metre is called power of lens in dioptre (D).
With a convex lens, the real image of a distant object is formed at a distance
equal to its focal length.

2)If f1 and f2 be the focal lengths of the two lenses and F be the focal length of
the combination.
1 1 1
𝐹
= 𝑓1
+ 𝑓2

3)Keep the white painted vertical wooden board to serve as a screen.

4)The convex lens (known focal length f1 = 15 cm), fixed into a holder stand is
put on the left of the screen. There is sunlight illuminated green trees at large
distance on the left of the lens.

5)The lens is moved towards and away from the screen till a sharp, inverted
image of​
trees is formed on the screen.

6)Distance between central lines of the screen and holder stand is measured by
a half​
metre scale.

7)The distance gives the focal length of the convex lens about 15 cm.

8)Replace first lens by second convex lens of required power and repeat the
steps from 2 to 5. This gives the focal length of second convex lens.
9)Now bring both lenses in contact and repeat the steps from 2 to 5. This gives
the​
combined focal length.

10)Determine the focal length with another given lens. Determine the focal
length of about six of the convex lenses.

POWER FOCAL LENGTH

𝑃1(𝐷) 𝑃2(𝐷) 𝑓1𝑖𝑛 𝑐𝑚 𝑓2𝑖𝑛 𝑐𝑚
2 8 50 12.5
4 6 25 16.7
5 5 20 20

Verification​
The above combinations may be tried and result verified.

Precautions

1)Thin lenses should be taken.

2)Lenses should have same aperture.

Sources of error

1)Lenses may not be thin.

2)Lens apertures may not be same.