Download Topic 2: Reflection

19/02/2013
Unit C: Lights & Optical Systems
Topic 2: Reflection
A. Introduction
1. Reflection is the process in which light strikes a
surface and bounces back off that surface. How
it bounces off the surface depends on the ____
___ ____________ and the type of surface it
hits. If it hits a rough surface, the light is ___________.
If it hits a smooth surface, the light _______________
____________________________ to the angle it hits.
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2. Light coming from a light source is called an
__________ ______ and the light that bounces
off the surface is called a __________ ______ .
3. A line that is ___________ ( 90o with the surface)
to the plane mirror is called the normal line.
4. The angle between the incident ray and the normal
line is called the angle of ____________ ( i ).
5. The angle between the reflected ray and the normal
line is called the angle of ____________ ( r ).
B. Forming An Image
1. The Law of Reflection states that:
_________________________________________
• The incident ray, the normal line and the reflected
ray lie in the same plane (an imaginary flat surface)
C. Curved Mirrors
1. Convex mirrors
a)
b)
Mirrors that __________ out
Convex mirrors form images that appear much smaller and
farther away than the the object - but they can reflect
light from a large area, making them useful as security
devices.
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2. Concave Mirrors
a) Mirrors that _________ in
b) Concave mirrors form an
image that appears to be closer
than it actually is and can be
useful because it can also reflect
light from a large area - side
mirrors on automobiles.
D. Using Reflections
1. Reflectors help to make _________ and
_________ visible at night.
2. A reflector is made up of hundreds of tiny, flat
reflecting _________ arranged at 90o angles to
one another.
3. These small surfaces are packed side by side to
make the _________ .
4. When light strikes the reflector the light
bounces off the tiny surfaces and bounces
_________ toward the light source.
5. Pool players use the law of reflection to
_________ their game.
6. Like a light ray, a pool ball travels in a
_________ line. In a 'bank shot' (Figure 3.25, p.
199) the cue ball is bounced off the cushion at an
angle which enables the player to hit the target
ball.
7. This angle is calculated as the angle of
_________ (with the cushion) is equal to the
angle of _________ (with the target).
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