Question

Two equal point charges of 3.4 e.s.u. are 17cm apart. What is the force on a unit positive charge situated 17 cm from each of the two charges and what is the direction of this force? What is the magnitude and direction of this force when the first two charges are of opposite sign?

Answer 1

Like charges act with a force F₁ = qe√(3/r) = 0.02 dyne in a direction perpendicular to the line joining the first two charges. Opposite charges act with a force F = qe/r² ≅ 0.01 dyne in a direction parallel to the line joining charges q (Fig.).