Question

A point object is placed on the principal axis of a concave mirror of focal length 20 cm. At this instant object is given a velocity v towards the axis (event-I) or perpendicular to axis (event-2). Then, speed of image

A. In event-1 is 2v
B. In event-1 is 4v
C. In event-2 is 2v
D. In event-2 is 4v

Answer 1

Correct Answer - A::B::C
`1/v+1/(-30)=(1/(-20)`
Solving we get, `v= -60 cm`
`m=(v)/(u)=-((-60))/((-30))=-2`
Speed of image (in event-1) is `m^(2)` times and m times in event-2.