Two identical beads each have a mass m and charge q. When placed in a hemispherical bowl of radius R with frictionless, non-conducting walls, the beads move, and at equilibrium they area distance R apart (figure). Determine the charge on each bead.

Answer

A, B, C, D

Explanation

Using Lami's theorem we have
`(mg)/(sin(90^@+30^@))=(mg)/(sin(90^@+60^@))`
`:. F=(mg)/sqrt3 or 1/(4piepsilon_0) ((q)(q))/R^2=(mg)/sqrt3`
`:. Q=sqrt(piepsilon_0mgR^2)/sqrt3`