Complete Question
The complete question is shown on the first uploaded image
Answer:
A

B

C
The correct option is B
Explanation:
From the question we are told that
The refractive index of water is 
The refractive index of ethanol is 
Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

Where c is the speed of light with value 


Generally the threshold velocity for creating Cherenkov light from a charged particle as it travels through water is mathematically evaluated as

=> 
=> 
The correct choice is
D. 22 Hz and 42 Hz.
In fact, the beat frequency is given by the difference between the frequencies of the two waves:

In this problem, the beat frequency is
, therefore the only pair of frequencies that gives a difference equal to 20 Hz is
D. 22 Hz and 42 Hz.
c. energy and object has.....
Which conditions I think you have place an incorrect image?
Answer:
Explanation:
The application of Gauss's law is used in the derivation as shown with detailed step by step in the attached file.
The potential difference on this spherical capacitor is ΔV = Va - Vb = kQ/a - kQ/b = kQ(1/a - 1/b)