Question

find the object distance for a concave mirror if the focal length is 5 cm and the real image is formed at the 10 cm from the mirror​

Answer 1

Explanation:

by mirror formula

1/f = 1/v +1/u

as it is a concave mirror so all v , u , f will negative

1/-5 = 1/-10 + 1/u

1/-5 +1/10

(-2 +1)/10

= -10 = u

there fore object distance from concave mirror is 10cm

Answer 2

Answer:

Object distance= -10cm

It means object is placed 20 cm in the front of mirror.

Explanation:

Focal length of concave mirror (f) = -5 cm

Image distance (v) = -10 cm

By using mirror formula,

1/f= 1/u + 1/v

1/u = 1/f - 1/u

= 1/-5 - 1/-10

= -1/10

Then ,u= -10cm.

Thanks