Question

A very small ball has a mass of 5.00 x 1023 kg and a charge of 4.00C. What magnitude electric field directed upward will balance the weight of the ball so that the ball is suspended motionless above the ground?

Answer 1

As $F=Eq$ and $F=mg$ hence $E=mg/q$ then $E=5.00\sdot10^{-23}/4\approx12.3\sdot10^{-23}V/m$ , where $E$ is the magnitude electric field