A concave mirror produces three times enlarged image of an object placed at 10cm in front of it. Calculate the focal length of the mirror

Answer:

Given

The concave mirror produces three times enlarged image of an object placed at 10cm in front of it.

Find out

We need to find out the focal length of the mirror

Solution

As per the given conditions,

m = 3 {A concave mirror produces three times enlarged image of an object and the }

u = -10 cm

Formula

We know that,

\(m = \frac{-v}{u}\)

Substituting the known values we get,

3 = (-v)/(-10)

v =  30

The distance between the mirror and image =   30 cm

From mirror formula, we know

\(\frac{1}{v}+\frac{1}{u}= \frac{1}{f}\)

 

⇒ \(\frac{1}{30}+\frac{1}{-10}= \frac{1}{f}\)

(-2)/30 = 1/f

or f = – 15

The radius of curvature R = 2f

∴ R = 2 × (- 15)

R = -30 cm

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