Question

An object is kept at a distance of 75cm from lens of power -4D Calculate the image distance

Answer 1

Answer:

• Distance of image is v = -30 and magnification is 0.4.

Explanation:

Given data:

Focal length "f" = 50 cm

Distance of object = 75 cm

Image distance can be found by using lens formula.

The formula is

1/f = 1/u - 1/v

We have f = 50, u = -75

1/50 = 1/(-75) - 1/v

1/50 + 1/75 = - 1/v

3+2 / 150 = - 1/v

1/v = 1/30

v = -30

Magnification is M=-v/u

M = 30 / 75

M = 0.4

• Hence the distance of image is v = -30 and magnification is 0.4.