Question

Difine Focal length.?​

Answer 1

Explanation:

the distance between the centre of a mirror or a lens and its focus

एक दर्पण या लेंस के केंद्रबिंदु से उसके फ़ोकस की दूरी; नाभीय दूरी

The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light.

IFormula

Formulaf=-\frac{R}{2}

Formulaf=-\frac{R}{2}f = focal length

Formulaf=-\frac{R}{2}f = focal length{R} = radius of curvature of the mirror's surface

Answer 2

Answer:The Distance between the Centre of a mirror or a lens and its focus....

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