Question

Find the magnitude of the focal length of a concave mirror whose radius of curvature is 25 cm.

Answer 1

Answer:

Given :-

Radius of Curvature = 25cm

To Find :-

Focal length of concave mirror = f

Solution :-

We know that focal length (f) is the half of the radius of curvature.

$focal \: length \: (f) = \frac{radius(r)}{2} \\ = > (f) = \frac{25}{2} = 12.5cm$

We know that,

Focal length of concave mirror is always negative

So, f = -12.5 cm

Answer 2

A N S W E R :

• The magnitude of the focal length is 12.5

Given :

• Radius of curvature = 25cm

• Type of mirror = Convex & Concave mirror

To find :

• Find The Focal Length ?

Solution :

As we know that,

• F = R/2

Where,

• F = focal length

• R = radius of curvature

=> F = 25/2

=> F = 12.5

Hence,

• The magnitude of the focal length is 12.5

More Information :

• 1/f = 1/v - 1/u
• m = -v/u
• F = R/2