Optics Question 668

Question: The focal length of lens of refractive index 1.5 in air is 30 cm. When it is immersed in a liquid of refractive index $ \frac{4}{3} $ , then its focal length in liquid will be

[BHU 2002]

Options:

A) 30 cm

B) 60 cm

C) 120 cm

D) 240 cm

Show Answer

Answer:

Correct Answer: C

Solution:

By using $ \frac{f _{l}}{f _{a}}=\frac{{( _{a}}{\mu _{g}}-1)}{{( _{l}}{\mu _{g}}-1)}\Rightarrow f _{w}=4f _{a}=4\times 30 $ =120 cm.



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक