Question

The power of a converging lens is 4.5 D and that of a diverging lens is 3 D. The power of this combination of lenses placed close together is (a) +1.5D
(b) +7.5D
(c) −7.5D
(d) −1.5D

Answer 1

Answer:

(a) +1.5D

Explanation:

Converging lens = +4.5D

Diverging lens = -3D

Therefore Total Power of Combined lens

= 4.5 + (-3)

= 4.5 - 3

= 1.5D

Answer 2

The power of a converging lens is 4.5 D and that of a diverging lens is 3 D. The power of this combination of lenses placed close together is +1.5 D

Explanation:

• The converging lens have the power of 4.5 D and the power of the diverging lens is 3 D.
• Then, the combination of lenses power becomes 1.5 D when they are placed close to each other.
• This is because of the fact that when the lens is placed in combination, the power adds up.
• So, net power is equal to 4.5 D + (-3.0 D), which results in 1.5 D.

Therefore the correct answer is Option (a) +1.5 D