Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • A point source of light is placed below the surface of water of refractive index <img alt="

A point source of light is placed \mathrm{4\ m} below the surface of water of refractive index \mathrm{5/3}. The minimum diameter of a disc, which should be placed over source, on surface of water to cut off all light coming out of water is:

Option: 1

\mathrm{1\ m}


Option: 2

\mathrm{4\ m}


Option: 3

\mathrm{3\ m}


Option: 4

\mathrm{6\ m}


Answers (1)

best_answer

Here, \mathrm{\sin C=\frac{1}{\mu}=\frac{1}{5 / 3}=\frac{3}{5}}
\mathrm{\therefore \quad \tan C=\frac{3}{4}}
If \mathrm{R} is radius of disc, then \mathrm{\tan \mathrm{C}=\frac{\mathrm{R}}{\mathrm{h}},}
\mathrm{\mathrm{R}=\mathrm{h} \tan \mathrm{C}=4 \times \frac{3}{4}=3 \mathrm{~m}}
Diameter of disc \mathrm{=2\ R=6\ cm}

Posted by

Ritika Kankaria

View full answer

JEE Main high-scoring chapters and topics

Study 40% syllabus and score up to 100% marks in JEE

Similar Questions

Trending Articles/News

anam-khan

JEE Main 2026 application correction begins on jeemain.nta.nic.in; edit details by December 2
anam-khan

JEE Mains 2026 LIVE: NTA to conduct session 1 from January 21 to 30; exam pattern, syllabus
anam-khan

JEE Main 2026 correction window opens tomorrow; NTA allows exam city change

Latest Question