A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the objecte distance?

Question

A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the objecte distance? (A) 36 cm (B) 25 cm (C) 30 cm (D) 150 cm

Tardigrade Admin · Accepted Answer

We have a lens of focal length 30 cm that produces 5 times magnified real image. So, we have (1/5u)- ((1/-u))=(1/30) Hence (1/5u)+ (1/u)+(5+1/5u)=(1/30) So, u = 36 cm

Q. A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the objecte distance?

36 cm

25 cm

30 cm

150 cm

We have a lens of focal length 30 cm that produces 5 times magnified real image.
So, we have
$\frac{1}{5 u} - (\frac{1}{- u}) = \frac{1}{30}$
Hence $\frac{1}{5 u} + \frac{1}{u} + \frac{5 + 1}{5 u} = \frac{1}{30}$
So, $u = 36 c m$

Q. A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the objecte distance?

36 cm

25 cm

30 cm

150 cm

We have a lens of focal length 30 cm that produces 5 times magnified real image. So, we have 5u1​−(−u1​)=301​ Hence 5u1​+u1​+5u5+1​=301​ So, u=36cm

We have a lens of focal length 30 cm that produces 5 times magnified real image.
So, we have
$\frac{1}{5 u} - (\frac{1}{- u}) = \frac{1}{30}$
Hence $\frac{1}{5 u} + \frac{1}{u} + \frac{5 + 1}{5 u} = \frac{1}{30}$
So, $u = 36 c m$