A small glass bead has been charged to 20 nC A tiny ball be

A small glass bead has been charged to + 20 nC. A tiny ball bearing 2.0 cm above the bead feels a 1.6 Times 10^-2 N downward electric force. What is the charge on the ball bearing? Express your answer using two significant figures.

Solution

F = k q₁ q₂ / r²

q₂ = F r² / k q₁

= (1.6 * 10^-2 * 0.02²) / (8.99 * 10⁹ * 20 * 10^-9)

= 3.56 * 10^-8 C

= 35.6 nC