The focal length of a diverging lens os 50 cm. The power of the lens is:

Correct option is B

The Correct Answer is (B) –2D

Explanation:

The power (PPP) of a lens is calculated using the formula:

​$$P= \frac{100}{f}$$​​

where:

• P = power of the lens (in diopters, D),
• f = focal length of the lens (in cm).

Step 1: Identify the focal length

• Given focal length (f) = 50 cm.
• Since it is a diverging lens, the focal length is negative: f=−50 cm.

Step 2: Substitute into the formula

​$$P=\frac{100}{f} = \frac{100}{-50} = −2D$$​​

Key Facts:

·         The focal length of a diverging lens is always negative.

·         A negative power indicates a diverging lens.

·         Power is measured in diopters (D), where 1D=1 m⁻¹.

·         Shorter focal lengths correspond to higher powers.