NEETPhysicsElectrostatics
A positively charged thin metallic shell of radius R is placed in a vacuum. Which of the following correctly describes the variation of the magnitude of the electric field E with radial distance r from the centre of the shell?
Options
- AE is constant and non-zero for r R .
- BE increases linearly with r for r R .
- CE is zero for r R .
- DE is zero for r R .
Correct answer
C. E is zero for r R .
Step-by-step solution
For a uniformly charged thin metallic shell of radius R carrying a total charge Q : Inside the conducting shell ( r Outside the shell ( r > R ), the shell behaves as if its entire charge is concentrated at the centre. By Gauss's law, the electric field is given by E = 1 4 ₀ Q r^2 . Thus, the electric field decreases proportionally to 1 r^2 . Therefore, E is zero for r R . Answer: E is zero for r R .