(b) reflection
   (c) refraction
   (d) total internal reflection
Ans: (a)
167. When a light ray is reflected repeatedly by a set of parallel plane mirrors,
   the intensity of light ray diminishes alter a few reflections. This is because of
   (a) poor reflection from the mirrors
   (b) scattering of light from the mirrors
   (c) absorption of some light by the mirrors
   (d) absorption of light by the atmosphere
Ans: (c)
168. The radius of curvature of a spherical mirror is
   (a) equal to half its focal length
   (b) equal to its focal length
   (c) twice its focal length
   (d) not related to its focal length
Ans: (c)
169. A convex mirror always produces
   (a) an erect, virtual image of diminished size
   (b) an erect, real image of diminished size
   (c) an erect, real image of double size
   (d) a virtual image of double size
Ans: (a)
170. To concentrate light on the defective teeth, the dentists use
   (a) convex mirrors
   (b) concave mirrors
   (c) convex lens
   (d) concave lens
Ans: (b)
171. Rays from the headlight of a motor car are rendered parallel by suitably
   (a) a convex mirror behind it