Question

A tiny 0.8g ball carries a charge of magnitude 10μC. It is suspended by a thread in a downward 500N/C electric field. What is the tension in the thread if the charge on the ball is positive?

Answer 1

The tension in the thread

$$T=mg+qE\\ =\rm 0.0008\: kg*9.8\: N/kg+10*10^{-6}\: C*500\: N/C$$ $$=0.0128\: N$$