Question

An object is placed 25 cm from a convex lens whose focal length is 10 cm. The image distance is ________ .

• A. 50 cm
• B. 16.66 cm
• C. 6.66 cm
• D. 10 cm

Answer 1

Answer: (B)

Given that,

Object distance, $u=-25cm,Focallength,f=10cm$

From lens formula, $\frac{1}{v}-\frac{1}{u}=\frac{1}{f}$

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

$⟹\frac{1}{v}=\frac{1}{10}-\frac{1}{25}$

$⟹\frac{1}{v}=\frac{5-2}{50}=\frac{3}{50}$

$⟹v=16.66cm$

Answer-(B)