Question

Find the electric field intensity of two charges 2C and -1C separated by a distance 1m in air.

(a) 18 X 10^9

(b) 9 X 10^9

(c) 36 X 10^9

(d) -18 X 10^9

The question was posed to me during an interview.

My question is from Electric Field Intensity in division Electrostatic Fields of Electromagnetic Theory

Answer 1

Correct option is (b) 9 X 10^9

The best explanation: F = q1q2/(4∏εor2) = -2 X 9/(10^-9 X 12) = -18 X 10^9

E = F/q = 18 X 10^9/2 = 9 X 10^9.