If charge Q=3uc having mass m=4×10^-6kg is in equilibrium between two oppositely charged plates separated by a distance d=60cm, find the potential difference of a power supply.
The potential difference of the power supply is equal to the electric field between the two plates. The electric field is equal to the charge divided by the distance between the plates, or E = Q/d. Therefore, the potential difference of the power supply is equal to 3uc/(60 cm) = 5 × 10^-4 V.
