Page 137 - Physics_Form_2

Nature and reflection of light
Questions
(a) What type of shadow was
formed on the screen?
(b) Where can similar shadow
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effects be found in daily life?
Project 4.1
Set up a light source and various
objects at different distances to explore
how shadows change with different
light sources and object positions.
Investigate the size and clarity of
shadows formed. Write the report of
your findings.
Exercise 4.1
1. You are in a room at night, and the
light is turned on. You can see the
furniture, walls, and other objects
even though they do not produce
light. Explain how you are able to
see non-luminous objects in such a
situation.
2. Imagine you are helping your school
administration to design an energy-
saving lighting system. Would
relying only on sunlight be effective
for classrooms? Justify your answer
based on daily lighting needs.
3. During a science club presentation,
a student shines a torch through a
hole in a cardboard. Describe the
difference between the terms “ray of
light” and “beam of light” in relation
to this demonstration.
Physics Form 2 Final.indd 131
4. Your parents are planning to build
new classrooms and has asked
for your input on design choices.
Which roofing materials would you
recommend to help reduce electricity
usage for lighting during the day?
Explain your choice.
5. Explain how the umbra and penumbra
are formed when light is blocked by
an object.
6. You are asked to create sharp
shadows of different objects using
a torch during a science exhibition.
Identify and explain the factors that
will affect how sharp the shadows
appear
Reflection of light through the plane
mirror
We see objects because they reflect the
light falling on them. When light rays
fall on the surface of an object, they are
either absorbed, transmitted, or reflected.
Sometimes, a combination of the above
processes may occur. When light strikes a
surface, how it is reflected depends on the
nature of the surface.
Reflection of light is the phenomenon
in which light rays are bounced back
when they strike a highly polished
surface like a mirror.
While one cannot usually see behind
oneself, by the use of a mirror, one can
see an object which is approaching from
behind. This is possible because the light
from the object, on falling on the mirror,
is thrown back to the observer’s eyes.
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