Electricity and light Date:
objectdoes not emit its own light (which accounts for light to
most objects in the world), it must reflect
example.
be seen. For
the ceiling
The walls in the room that you are in do not emit their own light; they reflect the light from
"ights"overhead.
glass mirrors.
Polished metal surfaces reflect light much |ike the silver layer on the back side of
beam of light incident on the metal surface is reflected.
e A construction
well. Other objects, like brown
Objectslike mirrors and white papers reflect light very
paper, do, not reflect
as much light. day, your
ever been near a pool on a sunny
goodat reflecting light offits surface. If you have
Wateris also block sunlight, but not the
water. Hats help
have hurt from too much light reflected from the
eyes may
reflected off the surface of water.
lightthatiis
to another
Refraction
they pass from one medium
appear bend when See how the
light bends
wondered why objects involved!
Have you ever refraction is
believe, especially when
doesn't always
medium?Seeing
pencil right before you.
like, "breaking" a
Tra
Refraction Phenomenon
Photocopying Prohibited 22
Electricity and light Date:
When you bend down untilyou are looking in line with the top of the water, It looks as thoueh the.
is broken in twol Light travels through different matertals, or mediums, at different Speeds in #hi.
experiment,light first travels through the air - which is easy to move through - and then throuok t
water, where it slows down.
This change in speed causes the light to bend, or refract, meaning that the part of the pencil that ie inte
water will
appear shifted- When light travels from air into water, it slows down, causing it to chanes
direction slightly. This change of direction is called refraction.
Manybirds hunt by flying over the surface of water, then diving in once they see a fish. Like in this
figure
the image a bird sees of a fish isn't where it really is; the image can be quite far
from the real fish. The
bird must adjust where it dives to catch the fish. This effect is also caused by
the refraction of light once it
hitsthe water.
Air
Water
Electricityand light
Date:
55. a. The diagram below shows what happens when a ray of light travels fromthe air, through a glass
block, then back into the air. Label the parts of the
diagram withthe following words.
Incoming light ray, refracted ray
ncomigny
Air
Glass
RefnarAAY
b. Explain the above diagram. fromttan
ight biael
travel eferent speels
eaeause the
In ditE ecent
he placed an empty glass at the top of
of smiley face on a piece of paper. Then
b. Ryan draws a picture seeing the picture he filled the
6 Light and the solar system
What is refraction?
Refractionis the bending of light.
Refraction occurs because light travels
light bends
at different speeds through different as it exits
mediums. A medium is amaterial such water
as water, glass or air.
Look at the picture of Sofia. She is
looking at the fish in the water. She where fitoshbecocecs
thinks the fish is in adirect line from real position of fish
her eyes. This is called an optical
illusion. An optical illusion is something
position of the fish.
our eyes see but which is not real. Look at the real
go from the water to the air.
The rays of light from the fish bend or refract as they
Think ike a scientist 1
Demonstrate how light travels whenit refracts
You will need:
aglass of water and a pencil
1 Predict what you will see when you put the pencil into the water.
Put the pencil into the glass of water.
2 Observe the pencil in the glass of water from the side.
3 Observe the pencil inthe glass of water from the top.
4 Take out the pencil. Has it changed in any way?
Questions
1 Did what you see match your prediction?
2 Draw a picture of the pencil in the glass of water from the side.
3 Draw a picture of the pencil in the glass of water from the top.
4 Why is what yousaw an optical illusion?
5 Which mediums does thelight pass through between the pencil
and your eyes?
orogresS
correct alternative for each of the following:
he
pendingof light is reflection/refraction.)
hoo
Th be
Apiece
#algsswith acurved surface is a lensfmirró,
perisCope uses mirrors
set at 90745° angles.
A the
Whenthelit up part of the Moon becomes bigger over a period of days,
d the Moon is(waxingwaning.
t nencil in the glass of water is atrick of the light/an optical ilusion.
Namethe rays 1 and2. 1
What word describes the angles that the rays
make withthe mirror and with the normal to
the mirror?
tafn is looking at astone in a container of water. The stone appears
pbe nearer the surface than it really is. Explain this using the
information on the diagram.
air
stone
appears to
be here water
stone
