Question

A partical revolves in clockwise direction (as seen from point A) in a circle C of radius 1 cm and completes one revolution in 2 sec. The axis of the circle and the principal axis of the mirror M coincides, call it AB. The radius of curvature of the mirror of 20cm. Then, the direction of revolution (as seen from A) of the image of the partical and its speed is

A. Clockwise, `1.57 cm//s`
B. Clockwise, `3.14 cm//s`
C. Anticlockwise, `1.57 cm//s`
D. Anticlockwise, `3.14 cm//s`

Answer 1

Correct Answer - A
By mirror formula : `(1)/(v)+(1)/(-10)=(1)/(10)`
`rArr v=+5 cm :. m=+(1)/(2)`
the image revolves in circle of radius `(1)/(2) cm`.
Image of a radius is erect `rArr` image will revolve in the same direction as the particle. The image will complete one revolution in the same the `2s`
velocity of image `v`
`=omega r=(2pi)/(2)xx(1)/(2)=(pi)/(2) cm//s=1.57 cm//s`.