Question

A point object is kept at the first focus of convex lens ,if the lens starts moving towards right will a constant velocity,th image will

A. always move towards right
B. always move towards left
C. first move towards right &then towards left
D. first move towards left &then towards right

Answer 1

Correct Answer - D
`(dv)/(dt)=((v)/(u))^(2)xx(du)/(dt)`
`V_("image/lens")=((v)/(u))^(2)xxV_("object/lens")`
till `u` become `2f mgt-1"so" V_("image/lens")gtV_("object/lens")` and image will moves towards left and when
`u "become" gt 2fV_("image/lens")ltV_("object/lens")`and image will moves towards right.