Question

what is the relation between the focal length and radius of curvature of a shperical mirror (concave mirror or convex mirror ) calculate the focal length of a shperical mirror whose radius of curvature is 25 cm​

Answer 1

Answer:

For a spherical mirror, the principal focus (F) lies exactly mid-way between the pole (P) and centre of curvature (C). So the focal length (f) of a spherical mirror is equal to half of its radius of curvature (R).

f=R/2

R=25cm(Given)

f=?

we know that

f=R/2

= 25/2

f= 12.5

So the answer is 12.5

Hope this would help you

Answer 2

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Focal length = 12.5 cm

${\huge{\boxed{\mathcal{\red{Explanation}}}}}$

Important keywords:

• Focal length of a spherical mirror is the distance between its focus and pole.
• Radius of curvature of a spherical mirror is the distance between it's pole and curvature.
• Curvature is the geometrical centre of the sphere whose mirror is a part of.
• Distance between focus and pole = distance between curvature and focus.

Now the relationship between focal length and radius of curvature of a mirror is - Radius of curvature of a mirror is double of its focal length.

It can be defined by following expression :

R = 2f.

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Now it is given that :

Radius of curvature of given mirror = 25cm

Focal length of mirror = ?

After inputting the following values in given equation we get:

$25 = 2f$

$f = \frac{25}{2}$

$f = 12.5cm$

Thus focal length of mirror is 12.5cm.

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BY SCIVIBHANSHU

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