1 a State which letter in Fig 1 represents the:
i incident ray ___________
ii reflected ray____________
iii normal __________________
iv angle of incidence __________________
v angle of reflection. ______________________
b Name the law that is demonstrated in Fig 1
Fig 1
2 List five properties of an image formed by a plane mirror.
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3 State which of the following alternatives makes each sentence true.
a Light is refracted away from/towards the normal when it passes from glass into air.
b Light travels at a higher speed through glass/air.
c Total internal reflection can only occur when light passes into a substance of lower/higher
refractive index.
4 Define the term lateral
inversion.__________________________________________________________________________
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5. Explain why light rays cannot originate from inside the
mirror.____________________________________________________________________________
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Teacher notes
Laws of reflection
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The angle of incidence = the angle of reflection.
The incident ray and reflected ray are in the same plane as, but on opposite sides of, the normal.
Images
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Real image – can be shown on a screen.
Virtual image – cannot be shown on a screen.
Plane mirrors
The image in a plane mirror has the following characteristics:
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virtual – it cannot be shown on a screen
upright and same size as the object
same distance behind the mirror as the object is in front
laterally inverted – back to front.
Images formed by curved mirrors
Note: focal point is the point where light rays converge to, or appear to converge from.
Convex Mirror
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The image is always virtual, upright and smaller in size.
The image cannot be shown on a screen.
Concave Mirror
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Object outside the focal point, the image is always real and upside down.
The image can be shown on a screen.
Object inside the focal length, the image is always virtual, upright and bigger.