Refraction Through a Lens — Question 10

As we know,

$\text{Power} = \dfrac{1}{\text{focal length}}$

Given,

Power of the lens = +2.0D

As the given power is positive,

Therefore, we can say that the lens used is convex in nature.

Substituting the value of power in formula we get,

$\text{2.0} = \dfrac{1}{\text{focal length}} \\[0.5em] \Rightarrow \text{focal length} = \dfrac{1}{2} \\[0.5em] \Rightarrow \text{focal length} = \text{0.5m} \\[0.5em] \Rightarrow \text{focal length} = \text{50cm} \\[0.5em]$

Therefore, the focal length is 50 cm and the lens used is convex in nature.