A point object at a distance of 36 cm from a convex lens of focal length 10 cm, is moved by 10 cm in 2 sec along principal axis towards the lens. Then image will aslo change its position.
a. Write the law which relates object and image distance from the lens.
b. Find the inwal and final position of the image and calculate average speed of image .
c. A man argues that the image will move uniformly at the same speed as that of object What is your opinion ? Justify.

Explanation

a. Lens maker.s formula `(1)/(f) = (1)/(v) - (1)/(u)`
b. `(1)/(f) = (1)/(v) - (1)/(u) `
`v_(i) = (uf)/(u + f) = (- 36 xx 10)/(-36 + 10) = (-360)/(-26) = 13.84` cm
`Y_(f) = (uf)/(u + f) = (- 26 xx 10)/(- 26 + 10) = (-260)/(-16) = 16.25 `cm
speed = `("distance " )/("time") = (16.25 - 13.84)/(2) = 1.205 ms^(-1) `
c. No. speed of the image is not unifomr eventhough speed of the object changes uniformly.