Question

Capacitance of a cylindrical capacitor is given by which of the following relation?

(a) C = \(\frac{∈l}{ln⁡(\frac{R}{r})}\)

(b) C = \(\frac{2πl}{ln⁡(\frac{R}{r})}\)

(c) C = \(\frac{2π∈l}{ln⁡(\frac{R}{r})}\)

(d) C = \(\frac{2π∈}{ln⁡(\frac{R}{r})}\)

This question was posed to me during an online interview.

Question is taken from Capacitive Transducer in section Transducers of Electrical Measurements

Answer 1

Correct option is (c) C = \(\frac{2π∈l}{ln⁡(\frac{R}{r})}\)

The explanation: The capacitance of a cylindrical capacitor is given by the relation

C = \(\frac{2π∈l}{ln⁡(\frac{R}{r})}\)

where, l is the length of the cylinder

R is the inner radius of the external cylinder

r is the outer radius of the inner cylinder.