Question

What will be permittivity of a medium which has dielectric constant 5.4?

(a) 4.78*10^-11 C^2N^-1m^-2

(b) 8.85*10^-10C^2N^-1m^-2

(c) 4.5*10^-10C^2N^-1m^-2

(d) 3.2*10^-11C^2N^-1m^-2

This question was addressed to me in final exam.

This key question is from Coulomb’s Law topic in section Charges and Fields of Physics – Class 12

Answer 1

Right option is (a) 4.78*10^-11 C^2N^-1m^-2

The explanation: εo=8.854*10^-12C^2N^-1m^-2. Therefore the permittivity will be 5.4*8.854*10^-12C^2N^-1m^-2 = 4.78*10^-11C^2N^-1m^-2. We know that permittivity of a medium is equal to its relative permittivity multiplied to the absolute permittivity of air. Air has relative permittivity =1.