72) The image formed by a plane mirror is always:

A) virtual and erect
B) virtual and inverted
C) real and erect
D) real and inverted

73) The distance between the pole and the principal focus of a spherical mirror is called:

A) image distance
B) object distance
C) focal length
D) radius of curvature

74) A diminished, virtual and erect image is formed by a

A) concave mirror
B) convex mirror
C) plane mirror
D) planoconcave mirror

75) The mirror used by a dentist to see a large image of the teeth of the patients is

A) concave mirror
B) convex mirror
C) plane mirror
D) plano-convex mirror

76) A ray of light travelling in air enters obliquely into water. This light ray

A) bends away from the normal
B) passes through the normal at the surface of separation
C) bends towards the normal
D) travels straight without bending