Question

The work done to move a charge of 20C by a distance of 2cm is 2J. What is the potential difference between those two points?

(a) 1V

(b) 0.1V

(c) 10V

(d) 20V

This question was posed to me in an interview.

The origin of the question is Potential Energy of a System of Charges topic in chapter Electrostatic Potential and Capacitance of Physics – Class 12

Answer 1

Right choice is (b) 0.1V

For explanation I would say: Work done to move a charge q in a potential difference of V is equal to q*V. According to the question, 2J=20C*Potential difference. Therefore, potential difference=\(\frac {2}{20}\)V=0.1V. The definition of 1J thus becomes, work done to move a charge of 1C from one point to another where the potential difference between the two points is 1V.