Question

A plane mirror is kept behind a convex lens at a distance of 5cm.when a pin is placed at a distance of 25cm from the lens then its image coincides with it,calculate focal length and power of the lens

Answer 1

we are clearly given all the clues to solving the question

u = -25 cm

v = 5cm ( cuz it is given the image formed coincides with the mirror so the mirror is acting as a screen for obtaining the image.

the lens formula is

1/f = 1/v - 1/u

1/f = 1/5 - 1/ -25

minus gets cancelled

1/f = 25+ 5/ 125

f = 125/30

f = 4.1 cm

therefore the power

d = 1/f

therefore the power is

1/4.1 = .24 diopters

plz mark as brainliest

byee

Answer 2

Answer: f = 25cm and P = 4D

Explanation: If the image of an object concide with it in case of convex lens there should be a plane mirror which turn the direction of the refracted light that meeting at focus of lens and image is formed.