Page 146 - Physics_Form_2
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Physics for Secondary Schools
is the value of the angle of reflection? a spherical or curved mirror. The type of
What is the angle between the curved mirror depends on which side of
incident ray and the reflected ray? the curved glass is silvered. If the outer
5. A girl in Figure 4.19 stands 80 cm side of the curved glass is silvered such
away from the plane mirror. If the that the inner side becomes reflective, the
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girl moves 20 cm towards the mirror, mirror is called a concave mirror (Figure
what is the distance between the girl 4.20(a)). Conversely, if the inner side of
and her image? Give a reason for the curved glass is silvered so that the
your answer. outer surface becomes reflective, the
mirror is called a convex mirror (Figure
4.20 (b)).
Coated
surface
Coated
surface
Reflective
surface
Reflective
80 cm surface
Figure 4.19 (a) (b)
Figure 4.20: (a) Concave, and (b) convex
6. A regular polygon has an exterior mirrors
angle of 45°. Determine how many
times it can be rotated through the Terminologies used in spherical
angle 45° and still coincide with mirrors
itself, excluding the starting position. Understanding spherical mirrors involves
key terms such as principal axis, focal
point, mirror vertex, focal length,
Reflection of light from curved mirrors and centre of curvature. The centre of
Have you ever observed that a car side curvature (C) is the centre of the sphere
mirror makes objects look smaller than from which the mirror is derived. The
their real size? Why does this happen? principal axis is the line through the
A mirror with a curved reflecting surface sphere’s centre that intersects the mirror
is called a curved mirror. It is formed by at the pole (P), which is the mirror’s
silvering a piece of curved glass. If the vertex. These concepts are essential
glass is considered a portion of a hollow for understanding how light reflects off
sphere, then the resulting mirror is called curved mirrors.
140
Student’s Book Form Two
Physics Form 2 Final.indd 140 25/10/2025 10:27
