Question

when an object is placed at a distance of 50cm from a concave mirror the magnification produced is 1/2when should the object be placed to get a magnetication of 1/5​

Answer 1

Explanation:

method 1.

u = -50 cm

m = -(1/2)

m = - (v/u)

-(1/2) = - v/-50

V = -25 cm

We know, 1/v + 1/u = 1/f

⇒ 1/-25 + 1/-50 = 1/f

⇒ -3/50 = 1/f

⇒ f = (-50/3) cm

method 2.

m = - (1/5)

f = (-50/3) cm

m = - (1/5) = - (v/u)

v = u/5

Now,

1/v + 1/u = 1/f

5/u + 1/u = -3/50

6/u = -3/50

u = 600/-3 = -100 cm