Question

Two lenses of power 2.50 D and -3.75 D are combined to form a compound lens. What will be its focal length (in centimetres)?

Answer 1

Answer:80 cm will be the focal length of the compound lens

Explanation:

Answer 2

Explanation:

2.50 is the power of lens 1

-3.75 is the power of lens 2

P1+P2=P of total

2.50+(-3.75)

2.50-3.75= -1.25

P=1/f so f=1/p

f=1/-1.25

=-0.8 m

The focal length in cm is 800cm.