Question

An object is placed at a distance of 10cm from a concave mirror if its image is observed at 6 cm from the mirror.calculate focal length of mirror

Answer 1

u = -10cm (s.c.)

v = -6cm

We know

1/f= 1/u+1/v

1/f=1/(-10)+1/(-6)

1/f=-6-10/60

1/f=-16/60

F=-60/16

F=-3.75m

Answer 2

Answer:-

Given:-

Distance of the object, (u) = 10 cm = -10 cm (sign convention)

Distance of the image, (v) = 6 cm = -6 cm (sign convention)

To Calculate:-

Focal length, (f) = ???

Formula to be used:-

⇒ $\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$

Substituting the given values,

⇒ $\frac{1}{f}=\frac{1}{-10}+\frac{1}{-6}$

⇒ $\frac{1}{f}=\frac{-6-10}{60}$

⇒ $\frac{1}{f}=\frac{-16}{60}$

⇒ $f=-3.75 \: cm.$

Hence, the focal length is 3.75 cm.