Question

Where should an objective placed in front of a concave mirror of focal length 20cm so as to obtain real image two times magnified

Answer 1

Answer :

f = -20 cm

m= -2

For mirror

m = -v/u

-2 = -v/u

v= 2 u

1/f=1/v+1/u

1/-20=1/2u+1/u

1/-20=3u/2u^2

2u= -60

u= -30 cm