Question

If an object is placed 25 cm in front of the converging lens forms an image 20cm behind the lens then what is the focal length of the lens

Answer 1

Answer:

v = image distance

u = object distance

f = focal length

1/v - 1/u = 1/f

1/20 - 1/25 = 1/f

5 - 4 /100 = 1/f

1 / 100 = 1/f

100cm = focal length

hope it helps you