Question

Focal length of a lens is 25 cm. Its power is___

• A. 5D
• B. 6D
• C. 4D
• D. 0.04D

Answer 1

The Correct Option is C

To solve the problem, we need to calculate the power of a lens whose focal length is given.

1. Formula for Power of a Lens:
The power \( P \) of a lens in diopters (D) is given by:
\[ P = \frac{100}{f(\text{in cm})} \]

2. Substituting the Given Focal Length:
Given: \( f = 25 \, \text{cm} \)
\[ P = \frac{100}{25} = 4 \, \text{D} \]

Final Answer:
The power of the lens is 4D (Option C).