Question

A light source is submerged inside water. It is moving in upward direction due to buoyancy force. Which of the following statements is incorrect?

• A. The percentage of light transferring from water to air is increasing.
  
• B. The percentage of light transferring from water to air is decreasing.
  
• C. Base area of light cone is increasing.
• D. Base area of light cone is decreasing.
  

Answer 1

Answer: (A), (C)

Base area of light cone is increasing.

Light will come out as the base of a cone of angle ${\sin }^{-1}\frac{1}{n}$ with a source at its vertex and radius of base, $r=\frac{h}{\sqrt{n^2-1}}$.


As the source moves upward, the base area will decrease, so the amount of light transferring will also decrease.