In a system containing three fixed point charges ,

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Electric Force Field and Potential · Electric Force Field and Potential

Problem

In a system containing three fixed point charges

q_1

q_2

, and

q_3

separated by distances

r_{12}

r_{23}

, and

r_{31}

, which expression gives the total electric potential energy

U

of the system? (a)

U=\dfrac12 k\left(\dfrac{q_1 q_2}{r_{12}}+\dfrac{q_2 q_3}{r_{23}}+\dfrac{q_3 q_1}{r_{31}}\right)

(b)

U = k\dfrac{q_1 q_2 + q_2 q_3 + q_3 q_1}{r_{12}+r_{23}+r_{31}}

(c)

U = k\left(\dfrac{q_1q_2}{r_{12}}+\dfrac{q_2q_3}{r_{23}}+\dfrac{q_3q_1}{r_{31}}\right)

(d)

U = k\left(\dfrac{q_1 q_2}{r_{12}}+\dfrac{q_2 q_3}{r_{23}}\right)