An object is put at a distance of 5 cm from the first focus of a convex lens of focal length 10 cm. If a real image is formed, its distance from the lens will be

Question

An object is put at a distance of 5 cm from the first focus of a convex lens of focal length 10 cm. If a real image is formed, its distance from the lens will be (A) 15 cm (B) 20 cm (C) 25 cm (D) 30 cm

Tardigrade Admin · Accepted Answer

(1/v)-(1/u)=-(1/f) (1/v)-(1/-15)=(1/f) or (1/v)-(1/15)+(1/10) or (1/v)=(-2+3/30) or v=30 cm

Q. An object is put at a distance of $5 c m$ from the first focus of a convex lens of focal length $10 c m$ . If a real image is formed, its distance from the lens will be

$15 c m$

$20 c m$

$25 c m$

$30 c m$

$\frac{1}{v} - \frac{1}{u} = - \frac{1}{f}$
$\frac{1}{v} - \frac{1}{- 15} = \frac{1}{f}$
or $\frac{1}{v} - \frac{1}{15} + \frac{1}{10}$
or $\frac{1}{v} = \frac{- 2 + 3}{30}$
or $v = 30 c m$

Q. An object is put at a distance of 5cm from the first focus of a convex lens of focal length 10cm. If a real image is formed, its distance from the lens will be

15cm

20cm

25cm

30cm