Question

define focal length and what is formula for focal length​

Answer 1

Explanation:

FOCAL LENGTH: THE DISTANCE BETWEEN THE OPTICAL CENTRE AND PRINCIPAL FOCUS OF A LENS

$\frac{1}{f} = \frac{1}{f1} + \frac{1}{f2}$

Answer 2

Answer:

The distance between the optical center and the principal focus of a spherical lens is known as the Focal length of a spherical lens. Formula used: 1u+1v=1f.

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