Question

if the magnifying power of magnifying glass is 3 , then focal length will be ...
a) 25cm
b) 12.5cm
c) 5cm
d)3cm...​

Answer 1

Answer:

HERE IS YOUR ANSWER⬇️

Explanation:

ANS is option c because cause length is always 5 in power 3.

Answer 2

Answer:

Focal length of lens is 12.5cm.

b) is the correct answer

Explanation:

If the image is formed at least distance of distinct vision. Then,

Magnifying power is given, $m=1+\frac{D}{f}$

where, D is the least distance of distinct vision = 25cm

f is the focal length.

$m$ is the magnifying power.

Putting in values in formula of $m$, we get,

$m=1+\frac{D}{f}$

$\implies 3=1+\frac{25}{f}$

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

$\implies f=\frac{25}{2} =12.5cm$

Focal length is 12.5cm

#SPJ3