Question

A concave mirror has f=30 cm. At what distance u should I place an object so that the image distance v equals u?

Answer 1

Explanation:

Here, u= -30 cm f= -20 cm By using mirror formula, 1/v + 1/u = 1/f 1/v + 1/-30 = 1/-20 v= -60 cm negative sign indicates that image is in front of

Answer 2

Answer:

Here,

u= -30 cm

f= -20 cm

By using mirror formula,

1/v + 1/u = 1/f

1/v + 1/-30 = 1/-20

v= -60 cm

negative sign indicates that image is in front of the mirror

Therefore,

The distance between image and object = 60–30 = 30cm