Question

Compute the capacitance between two concentric shells of inner radius 2m and the outer radius is infinitely large. (a) 0.111 nF (b) 0.222 nF (c) 4.5 nF (d) 5.4 nF This question was addressed to me during an online interview. My question is from Resistances and Capacitances in section Electrostatic Boundary Value Problem of Electromagnetic Theory Select the correct answer from above options Electromagnetic Theory questions and answers, Electromagnetic Theory questions pdf, Electromagnetic Theory question bank, Electromagnetic Theory questions and answers pdf, mcq on Electromagnetic Theory pdf,electromagnetic theory book pdf,electromagnetic theory pdf notes,electromagnetic theory lecture notes,electromagnetic theory of light,maxwell electromagnetic theory,electromagnetic theory proposed by,electromagnetic theory engineering physics,electromagnetic theory nptel

Answer 1

The correct choice is (b) 0.222 nF The explanation is: The concentric shell with infinite outer radius is considered to be an isolated sphere. The capacitance C = 4πε/(1/a – 1/b). If b->∞, then C = 4πεa. Put a = 2m, we get C = 4π x 8.854 x 10^-12 x 2 = 0.222 nF.