Question

a lens is formed by combining 2 thin lenses of power +12 and -8 in contact with each other. What will be the focal lenth of this combination

Answer 1

Answer:

1/4

Explanation:

Given,

P1= 12

P2=-8

We know that reciprocal of the focal length is power of the lens.

i.e P = 1/f

P1+P2 =1/f

12 + (-8) = 1/f

4=1/f

therefore, f=1/4.

Answer 2

Given,

P1= 12

P2=-8

We know that reciprocal of the focal length is power of the lens.

i.e P = 1/f

P1+P2 =1/f

12 + (-8) = 1/f

4=1/f

therefore, f=1/4.