Question

Find the flux density of line charge of radius (cylinder is the Gaussian surface) 2m and charge density is 3.14 units?

(a) 1

(b) 0.75

(c) 0.5

(d) 0.25

I have been asked this question in a job interview.

My doubt is from Electric Field Density in portion Electrostatic Fields of Electromagnetic Theory

Answer 1

Correct answer is (d) 0.25

For explanation: The electric field of a line charge is given by, E = λ/(2περ), where ρ is the radius of cylinder, which is the Gaussian surface and λ is the charge density. The density D = εE = λ/(2πρ) = 3.14/(2π X 2) = 1/4 = 0.25.