SUBJECT: SCIENCE

LESSON #1 Earth acts like a giant magnet because it generates

magnetic field and has a north and south
Electricity- is the term given to a group of physical
phenomena involving electric charges, their motions and
their effects.
Magnetism- is the study of magnetic fields and their
effect on materials. This effect, due to unbalanced spin
of electrons in atoms.
Electricity and magnetism are closely related. Flowing
electrons produce a magnetic field, and spinning
magnets cause an electric current to flow.

Magnetic field – is a region in space in which a

magnetic force can be detected.
 Magnetic flux – the number of magnetic field
lines per area
 Tesla (T) – SI unit of magnetic field strength in
honor of physicist Nikola Tesla
PROPERTIES OF MAGNETS
 Magnets have the ability to attract materials that
are magnetic in nature.
CLASSIFICATION OF MATERIALS (according to
how they are affected by the magnetic field)
HISTORY OF MAGNET
1. FERROMAGNETIC
In a distant land in Asia Minor, thousands of
 materials which are strongly attracted to
years ago, the Greeks discovered that certain metallic
magnets. Ferromagnetic materials
rocks (lodestones) in the district of Magnesia could
exhibit a long-range ordering
attract or repel similar rocks. They referred to these
phenomenon at the atomic level which
rocks as magnets in honor of the place where the rocks
causes the unpaired electron spins and
were discovered.
line up parallel with each other in a
region called a domain. E.g. iron. nickel,
cobalt, steel, gadolinium.
 The English 2. PARAMAGNETIC
man William  materials which have a small positive
Gilbert (1540-1603) susceptibility to magnetic fields. They
was the first to are slightly attracted to magnets. E.g.
investigate the aluminum, platinum, chromium
phenomenon of sulphate, crown glass
magnetism 3. DIAMAGNETIC
systematically using  materials create a magnetic field in
scientific methods. opposition to an externally applied
He also discovered magnetic field, thus causing a repulsive
that the Earth is itself effect. E.g. Gold, silver, copper,
a weak magnet mercury, quartz, water, alcohol, air,
bismuth, antimony, cloth and fabric.
  used every day in clothing, fashion accessories,
and home decor. Sewing disc magnets into
clothing is a great way to hold fabric together.
Industrial-sized disc magnets are commonly
used to pick up old cars at junkyards.
KINDS OF MAGNET
 Permanent magnets – are those we are most
familiar with, such as the magnets hanging onto
our refrigerator doors. They are permanent in the
sense that once they are magnetized they retain a
level of magnetism.
 Temporary magnets – are those which act like
a permanent magnet when they are within a
strong magnetic field, but lose their magnetism
when the magnetic field disappears. Examples
would be paperclips, nails and soft iron items.
Horseshoe magnets – bar magnets bent in a U shape LESSON #2
 Makes the magnet stronger by pointing the poles HANS CHRISTIAN OERSTED
in the same direction
 Was the first to show that an electric current can
 Small horseshoes can collect paper clips, produce magnetic fields
industrial-sized horseshoe magnets are used in
construction and engineering to pick up large  Discovered the relationship of electricity and
pieces of heavy metals magnetism during a class demonstration that a
current carrying wire caused a nearby
 Also used at the bottoms of pendulums magnetized compass needle to deflect
Ring magnets - round with a hole in the middle, and ELECTROMAGNETS – are tightly wound helical coil
because of this shape they are sometimes referred to as of wire, usually with an iron core, which acts like a
donut magnets. permanent magnet when current is flowing in the wire.
 used in science experiments such as a 3 WAYS TO CHANGE THE STRENGTH OF AN
demonstration of magnetic repulsion where the ELECTROMAGNET
magnetic rings are threaded through a wooden
pole. When the same poles of the magnets face  Increase the no. of turns of the coil
each other they won’t touch  Increase the current
Cylindrical magnets - used in medicine. Some doctors  Using an iron core
experiment with magnetic rods to treat scoliosis patients
SOLENOID
Bar magnets – magnet’s power is focused at the poles
and lessens at the sides.  a type of electromagnet when the purpose is to
generate a controlled magnetic field.
 Generally the weakest shapes because the poles
have the smallest area USES OF ELECTROMAGNETS

 Most common shape used in everyday life such  Electromagnets are very widely used in electric
as refrigerator magnets and compasses. and electromechanical devices like motors,
generators, transformer, electric bells, buzzers,
Disc magnets - because of the wide, flat surface, disc loudspeakers and earphones.
magnets have a large pole area making them strong,
effective magnets.
  Magnetic separation equipment used for
separating magnetic from non-magnetic
materials.

ELECTROMAGNETIC INDUCTION
Production of electric current across a conductor when
exposed to a changing magnetic field
FARADAY’S LAW OF ELECTROMAGNETIC
INDUCTION (MICHAEL FARADAY)
 Any change in the magnetic field of a coil of FACTORS THAT DETERMINE THE AMOUNT
wire will cause an emf to be induced in the coil. OF INDUCED CURRENT
 This emf induced is called induced emf and if 1. Moving the coil or the magnet faster
the conductor circuit is closed, the current will
also circulate through the circuit and this current 2. Increasing strength of the magnetic field
is called induced current.
3. Increasing the number of turns/ length of the coil
LENZ’S LAW (HEINRICH LENZ)
 The direction of the induced emf or induced
current is such that it opposes the change that is
producing it.
RIGHT HAND RULE
 Is based on the underlying physics that relates IMPORTANT POINTS TO REMEMBER:
magnetic fields and the forces that they exert on
 The region of magnetic field in a straight
moving charge
conductor is represented in concentric circles
MAGNETIC FIELD IN A STRAIGHT around the wire
CONDUCTOR
 Current flowing in each arm of the circular loop
is mutually opposite in directions
 The magnetic field is circular near the arm and
almost parallel, uniform and maximum at the
center of a looped conductor
 As the distance from the center of the circular
loop increases, the magnetic filed intensity
decreases
 The magnetic lines of force increases as the
current increases
FLEMING’S LEFT HAND RULE (JOHN
AMBROSE FLEMING)
 To determine the direction of the magnetic field,
Thumb – current
current and force (applicable in electric motor)
Fingers –magnetic field

MAGNETIC FIELD IN A LOOPED CONDUCTOR

LESSON #3
Andre-Marie Ampere 6. Photon – When light acts as particles, the
particles are called photons
✔ one of the founders of the science of classical
electromagnetism, which he referred to as 7. Photoelectric Effect – when a beam of light
"electrodynamics". The SI unit of measurement shines on some substances, it causes tiny
of electric current, the Ampere (A) is named particles called electrons to move. PROOF OF
after him. LIGHT AS PARTICLES!

✔ demonstrated the magnetic effect based on the 8. All electromagnetic waves travel at the same
direction of current speed (3 x 10⁸) but they have different
wavelengths and different frequencies
Michael Faraday
Speed = wavelength x frequency
✔ Formulated the principle behind electromagnetic
LESSON #4
induction
Electromagnetic Waves
Heinrich Rudolf Hertz (German)
✔ Transmission of energy through a vacuum or
✔ proved the existence of electromagnetic waves
using no medium , caused by the osscilation of
theorized by James Clerk
electric and magnetic fields.
Maxwell's electromagnetic theory of light.
✔ They move at a constant speed of 3x108 m/s.
✔ discovered the Hertzian waves which is known
Often, they are called electromagnetic
as radio waves.
radiation, light, or photons.
James Clerk Maxwell

✔ contributed developing equations showing the

relationship of electricity and magnetism

✔ Maxwell demonstrated
that electric and magnetic fields travel through
space as waves moving at the speed of light
Hans Christian Oersted

✔ Showed how a current carrying wire behaves

like a magnet
NATURE OF ELECTROMAGNETIC WAVES
EM Wavelength Frequency Energy
1. Electromagnetic Waves – transverse waves that
WAVE (m) (Hz) (J)
consist of changing electric and magnetic fields
2. Electromagnetic Radiation – the energy that is
Radio > 1 x 10-1 < 3 x 109 <2x
transferred by electromagnetic waves
wave 10-24
3. Speed of Electromagnetic waves – 3 x 10⁸ m/s in
a vacuum
Microwave 1 x 10-3 – 1 3 x 109 – 3 2 x10-
4. Light waves or Particles – light has many of the x 10-1 x 1011 24 – 2
properties of waves . But light can also act as a x 10-
stream of particles.
22
5. Polarized Light – Light as a wave can pass
through a polarized filter. PROOF OF LIGHT
AS A WAVE Infrared 7 x 10-7 – 1 3 x 1011- 2 x 10-
x 10-3 4 x 1014 22 – 3
 ✔ Photons are bundles of wave energy. The
x 10-
energy of a photon is given by the equation :
19
E = hf
Where h is the Planck’s constant equals to 6.63 x 10 ⁻³⁴
Visible 4 x 10-7 – 7 4 x 1014 – 3 x 10-
Joules per second
x 10-7 7.5 x 19 – 5
x 10-
1014
19

Ultraviolet 1 x 10-8 – 4 7.5x 1014 5 x 10-

(UV) x 10-7 –3x 19 – 2
x 10-
1016
17

X-ray 1 x10-11 – 3 x 1016 – 2 x 10-

1x 10-8 3 x 1019 17 – 2
x 10-
14

Gamma < 1 x 10-11 > 3 x 1019 >2x

ray 10-14

Electromagnetic Spectrum
A continuum of electromagnetic waves arranged
according to frequency and wavelength

✔ The different types of electromagnetic waves are

defined by the amount of energy carried by /
possessed by the photons
 SPECULAR OR
REGULAR
REFLECTION – light that
strikes a smooth, flat and
shiny surface, such as a
mirror, a piece of metal or
undisturbed water is
reflected in one direction. It
enables us to see an image on the surface.
DIFFUSE
REFLECTION
– light that is
reflected by a
rough-textured or
uneven surface as
wall, paper and
cloth is scattered
in many different
LESSON #5
direction. Diffuse
REFLECTION OF LIGHT reflection allows
us to see objects
It is the bouncing back of light on a surface of a medium. from any angle.
Only part of the incident ray is being reflected by that
surface. The rest is either absorbed by the object if it is
an opaque object or transmitted if the object is
PLANE MIRROR - simplest form of mirror which has
transparent like water.
a flat reflecting surface.
LAW OF REFLECTION
Multiple images are formed by the reflection that
1. States that the incident ray, the reflected ray and happens when arranging at least 2 mirrors
the normal are all lie on the same plane.
Parallel mirrors produced infinite number of images
2. States that the angle of incidence is equal to the
The mirror images (N) can be determined using the
angle of reflection
formula N=(360/angle between the mirror)-1
 A plane mirror makes an image of objects in front of USES OF PLANE MIRROR
it; these images appear to be behind the plane in
Used to see ourselves
which the mirror lies.
Fixed on the wall of certain shops to make them look
Image Formed by Plane Mirror
larger
The image is virtual
Used as decorations
The image is upright
Used in making periscopes
The image formed has the same size as the object
CURVED MIRROR
The image is as far behind the mirror as the object is
mirror with a curved reflective surface
in front of the mirror
convex (bulging outward)
The object and the image is perpendicular to the
mirror concave (bulging inward).
The image is Most curved mirrors have surfaces that are shaped
laterally like part of a sphere, but other shapes are
inverted sometimes used in optical devices.
(left-to-
right Convex mirror
inversion) Also known as fish eye mirror or diverging
mirror, is a curved mirror in which the
reflective surface bulges toward the light source.

TYPE OF IMAGE
1. VIRTUAL
- is one which seems to be form by light coming from
the image but no light rays actually pass through it

- Image cannot be projected on a screen

- Always upright
2. REAL
- Formed by the actual intersection of light rays
after encountering a mirror
- Can be projected on a screen Convex mirrors formed images that are always
virtual, upright and smaller than the object
- Always inverted
 USES OF CURVED MIRROR
Convex mirror
lets motorists see around a corner.
used in some automated teller machines as a simple
and handy security feature, allowing the users to
see what is happening behind them.
Used by some camera phones to allow the user to
correctly aim the camera while taking a self-
portrait
Concave Mirror
used in some telescopes.
Concave mirror
used to provide a magnified image of the face for
Also known as converging mirror, has a reflecting applying make-up or shaving.
surface that bulges inward (away from the
incident light). Used as reflectors in headlights and searchlights

Concave mirrors reflect light inward to one focal Dentist’s head mirror
point. They are used to focus light.
Unlike convex mirrors, concave mirrors show
different image types depending on the distance
between the object and the mirror.

parts of a curved mirror and their description

Parts of a Symbo Description

curved l
Mirror

Vertex/ V The physical centre of

the mirror
pole C
The geometrical centre
Centre of
of the curved mirror
Curvature
 Principal F The midpoint of the line
Focus between the vertex and
the center of curvature

Focal length f The distance between

the focal point and the
vertex

Principal Line drawn through the

axis/optical center of curvature &
axis vertex of the mirror

Aperture Diameter of the

reflecting surface, width
of the mirror

Ray diagram
1. A ray of light parallel to the principal axis is
reflected through the principal focus.
2. A ray of light passing through the principal
focus is reflected parallel to the principal axis.
3. A ray of light passing through the center of
curvature is reflected back along its own path.