Question

THE POWER OF A LENS IS 2.5DIOPTRE.
WHAT IS THE FOCAL LENGTH AND THE TYPE OF LENS?

Answer 1

$\large\underline{\underline{\sf Given:}}$

• Power of lens (P) = 2.5 D

$\large\underline{\underline{\sf To\:Find:}}$

• Focal Lenght of lens (f) = ?

• Type of lens = ?

$\large\underline{\underline{\sf Solution:}}$

We know that ,

${\boxed{\sf Power\:Of\:Lens=\frac{1}{f} }}$

$\large\implies{\sf 2.5=\frac{1}{f}}$

$\large\implies{\sf f=0.4m\:or\:40cm}$

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•°• $\large\underline{\underline{\sf Answer:}}$

$\underline{\underline{\sf Focal\:lenght\:of\:lens(f)\:is\:40cm}}$

And

$\large\underline{\underline{\sf Type\:of\:Lens\:is\:convex}}$

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Extra Info.

Power of convex lens is Positive .

Power of concave lens is Negative.

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