Question

What is the distance and magnification of the object, if image formed on a screen is 50cm from the lens of focal length 25cm? *

a) 50 cm and -1

b) 50 cm and 1

c) -50 cm and -1

d) -50cm and 1​

Answer 1

Explanation:

Given that, Focal length, f = 25 cm Image distance, v = 50 cm Form the lens formula, Or, u = −50 cm Magnification, The object must be placed 50 cm away from the lens, on the other side to produce a magnification of −1.

Answer 2

1/f = 1/v - 1/u

1/u=1/v -1/f

1/u = 1/50-1/25

1/u=1-2/50

1/u = -1/50

u =-50

m = v/u

m= 50/-50

m=-1

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