Question

If the object distance in the following picture were 8.0 m and the image distance were 2.0 m, what is the focal length?

Answer 1

the answers is -8/3m.

Step-by-step explanation:

Use 1/v- 1/u=1/f

v=image distance

u=object diatance

f=focal length

Answer 2

Focal Length = f = - 8/3 m

Step-by-step explanation:

Considering the lens is concave and for concave lens image distance and focal length are negative.

Image distance = q = -2 m

Object distance = p = 8 m

Focal Length = f = ?

Using concave lens formula,

1/f = 1/p + 1/q ………… (i)

By putting values in equation (i)

1/f = 1/8 -1/2

1/f = 1-4/8

f = -8/3 m