Question

A positive charge, q1, of 5 µC is 3 × 10–2 m west of a positive charge, q2, of 2 µC. What is the magnitude and direction of the electrical force, Fe, applied by q1 on q2?

magnitude: 3 N
direction: east
magnitude: 3 N
direction: west
magnitude: 100 N
direction: east
magnitude: 100 N
direction: west

Answer 1

F = k q1 q2 / r^2 = (8.99×10^9)(5×10^−6)(2×10^−6)/(3×10^−2)^2 ≈ 100 N.

Both charges are positive so q1 repels q2; since q1 is west of q2, the force on q2 is to the east.

Answer: magnitude 100 N, direction east.