Two identical spheres with mass m are hung from silk threads of length L, as shown in Fig. 21.44. Each sphere has the same charge, so q1 = q2 = q. The radius of each sphere is very small compared to the distance between the spheres, so they may be treated as point charges. Show that if the angle θ is small, the equilibrium separation d between the spheres is d = (q2L/2πє0mg) 1/3. (Hint: If 6 is small, then tan θ ≡sin θ.)

L. mass m mass m charge q2 charge q