Question

There are two lenses having focal length of -25cm and +20 are the nature of the lenses. Calculate power of each lens and total power of the combination of two lenses.

Answer 1

The power of each lens is -4 D and 5 D respectively. The total power of the combination of two lenses is 1 D.

Step-by-step explanation:

The power of a lens is calculated using the formula:

Power = 1/focal length

To find the power of each lens, we need to convert the focal length to meters. For the lens with a focal length of -25 cm:

Power = 1/(-0.25 m) = -4 D

For the lens with a focal length of +20 cm:

Power = 1/(0.2 m) = 5 D

To find the total power of the combination of two lenses, we simply add the individual powers:

Total Power = -4 D + 5 D = 1 D