Find the focal length of a lens of power – 2.0 D. What type of lens is this?
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Power of lens (P) = -2.0 D$\text{P} = \frac{1}{\text{f}}\text{ or f } = \frac{1}{\text{P}}$
$\text{f} = \frac{1}{-2.0}= -0.5 \text{m.}$
(-ve) sign of focal length means that the lens is concave lens.
$\text{f} = \frac{1}{-2.0}= -0.5 \text{m.}$
(-ve) sign of focal length means that the lens is concave lens.
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