Question

A focal length of a lens is 10 cm What is power of a lens in dioptre ?

• A. 0.1 D
• B. 10 D
• C. 15 D
• D. 1 D

Answer 1

Answer: (B)

Focal length of the lens $f=10cm=0.1m$
Power oflens $P=\frac{1}{f}$
$\therefore P=\frac{1}{0.1}=10D$