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

The force, $F$ due to upward electric field, is given by$Eq$

That is $F=Eq$

At balance point $F=Eq=mg$

$E=\frac{mg}{q}=(\frac{5\times1023\times9.8}{4})$ $=12531.75\frac{N}{C}$