Question

focal length of a concave mirror is 20 cm find the position of image of an object which is kept 30 cm in front of mirror

Answer 1

Answer:

use 1/u-1/v=1/f

Explanation:

.............u is object distance

v is image distance

f is focal length

Answer 2

Answer:

60cm real and inverted

Explanation:

1/f= 1/u+ 1/v

1/20 = 1/30 + 1/v

1/20 + 1/30 = 1/v

then we get LCM of 1/20 and 1/30.

3-2/60 = 1/v

1/60= 1/v

v = 60 cm. Ans