BES22/BES22L
Activity #1 Electrostatics
Instructions: Provide complete solutions. Write your solutions as neatly as possible. Don’t forget to write
your name on the sheet of your solutions.
1. Calculate the electrostatic force of repulsion between two particles when at a distance of 10-13
m from each other. Assume Q=3.2x10-19C.
2. Calculate the distance of separation between two electrons (in vacuum) for which the electric
force on one of them is equal to the gravitational force at the earth’s surface. Mass of
electron=9.1x10-31 kg, Charge of electron = 1.6x10-19 C
3. Two positive charges of 10 statcoulomb each are located 2 cm apart. What is the electrostatic
force?
4. Three equal positive charges of 10 statcoulomb each are located at the vertices of an equilateral
triangle of 2 cm leg. What is the magnitude of the force acting on each charge?
5. An isolated positive point charge of 2x10-8 coulombs is in free space. How far away must the
charge be in order to produce an electric potential of 120 volts?
6. Calculate the magnitude of the electric field at a point that is 30 cm from a point charge Q=3.2x10-6 C.
7. Calculate the capacitance between two parallel plates each of which is 100 cm2 and 2 mm apart
in air.
8. A parallel-plate capacitor has an equivalent capacitance of 850 pF (pico-farad). The area of each
plate is 6 cm2 and the thickness of the dielectric is 0.02 cm. IF the material used as the dielectric
has a constant of 8, how many sections are there in parallel?
9. Three capacitors of 10,13,17 micro-farad respectively are connected in series to a 100 volts
battery. Calculate the total charge of the circuit.
10. Two capacitors are connected in parallel to a 120V battery. The capacitors has a capacitance of
10 and 15 micro-farad, respectively. Calculate the total charge of the circuit.