Question

What is the dielectric strength of mica?

(a) 10 * 10^6 Vm^-1

(b) 100 * 10^6 Vm^-1

(c) 25 * 10^6 Vm^-1

(d) 15 * 10^6 Vm^-1

The question was asked in a national level competition.

This interesting question is from Polarisation and Dielectrics topic in section Refractories & Dielectric Materials of Engineering Material & Metallurgy

Answer 1

Right answer is (b) 100 * 10^6 Vm^-1

To explain: Dielectric strength is defined as the least amount of applied voltage that would result in a rupture. Mica is an important dielectric material having a dielectric strength of 100 * 10^6 Vm^-1 and a dielectric constant of 8 at 60 Hz. The dielectric strength of fused silica, vulcanized rubber, and Bakelite are 10 * 10^6 Vm^-1, 25 * 10^6 Vm^-1, and 15 * 10^6 Vm^-1 correspondingly.