Two identical insulating spheres each carry a positive charge of
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential
Problem
Two identical insulating spheres each carry a positive charge of +3.0μC. They are to be placed along a straight line so that the electric potential energy stored in the two–sphere system is exactly +0.120J.
Answer the following questions. Use k=8.99×109Nm2C−2 in any numerical work.
(a) Show algebraically how one may determine the required separation d between the centers of the spheres in terms of the desired potential energy U and the given charge magnitude q.
(b) Compute the numerical value of d that satisfies the energy requirement. Provide your answer in centimeters with the correct number of significant figures.
(c) Explain, in words, why the calculated potential energy is positive even though both charges are positive.
(d) If both charges were simultaneously doubled while maintaining the same separation d, by what factor would the potential energy of the system change? Justify your answer mathematically.