Electrostatics Worksheet Name ___________________________________________________________ Period ____

Electric Force: F = k_e q₁q₂ Gravity Force F == G m₁m₂ 1 C = 6.241E18 Electric Potential V = Work/q

d² d²

k_e = 9E9 Nm² G = 6.67E-11 Nm² 1 amp = 1C/s Electric Field E = k_eq (N/C) F = qE Capacitance = Q/V

C² kg² d²

e^-1 mass = 9.11E-31 kg e^-1 charge = -1.6023073E-19 Proton mass = +1.67E-27 kg Proton charge = 1.6023073E-19

1. An object with 4E8 excess electrons has what net charge? [6.4E-11 C]

2. An object has a net positive charge of 6 Coulombs. How many more protons does it have? [3.75E19]

3. An object cannot have a net charge of 1.2E-18 C? Explain why.

4. A conductor carrying a net charge of eight protons is brought into contact with an identical conductor with no net charge.

a. What will be the charge on each conductor after they are separated?

b. What is the charge of each conductor in Coulombs after they are separated? [6.4E-19 C]

5. The electron and proton of a hydrogen atom are separated, on average, by a distance of about 5.3E−11 m.

a. Find the magnitude of the electric force that each particle exerts on the other. [-8.2E-8N]

b. Find the gravitational force between the two. [3.6E-47]

c. Calculate how many times larger the electrostatic force is. [-2.2E39]

6. Two protons in the iron nucleus are 4.0E-15 meters.

a. What is the Coulomb force that exists between them? [14.4N]

b. What other forces stop the nucleus from flying apart?

7. Two electrostatic point charges of +60.0μC and +50.0μC exert a repulsive force on each other of 175 N. What is the distance between the two charges? [3.90E-1 m = 39.0 cm]

8. Two identical conducting spheres are placed with their centers 0.30 m apart. One is given a charge of +12E−9C and the other is given a charge of −18E−9C.

a. Find the electric force exerted on one sphere by the other. [-2.16E-5 N]

b. The spheres are connected by a conducting wire. Find the electric force between the two spheres. [3.6E-6 N]

9. Two positive charges of 6.0 E–6 C are separated by 0.50 m.

a. Draw a force diagram for each of the charges, considering only electrostatic forces.

b. What is the magnitude of the force between the charges? Is this force repulsive or attractive? [1.30 N]

10. Rocco, an auto body painter, applies paint to automobiles by electrically charging the car’s outer surface and oppositely charging the paint particles that he sprays onto the car. This causes the paint to adhere easily to the car’s surface. If two paint particles of equal charge experience a force of 4.0E-8 N between them at a separation of 0.020 cm, what is the charge on each? [3.6E-2 C]

11. After unpacking a shipment of laboratory glassware, Mrs. Payne dumps the box of Styrofoam into a recycling bin. The chips rub together and two chips 0.015 m apart repel each other with a force of 6.0E-3 N. What is the charge on each of the chips? [1.5E-16 C]

12. Wiz, the cat, is batting two Ping-Pong balls hanging from insulating threads with their sides just barely touching. The balls each acquire a positive charge of 3.5E-9 C from Wiz’s fur and swing apart. If a force of 6.0E-5 N acts on one of the balls, how far apart are they from each other? Is the force between them one of attraction or repulsion? [19 cm]

13. A particle of ink in an ink-jet printer carrying a charge of 8.0E-13 C is deflected onto the paper by a force of 3.2E-4 N. How strong is the field that causes the force? [4.0E 8 N/C]

14. What is the electric field intensity at a point where a proton experiences an electrostatic force of 2.3E-25 N? [1.44E-6 N/C]

15. The electric force on an electron is 2.00E-15 N, what is the magnitude of the electric field? [1.25E4 N/C]

16. A potential difference of 10 volts exists between two points, A and B, within an electric field. What is the magnitude of charge that requires 2E-2 Joules of work to move it from A to B? [2E-3 C]

17. How much electrical energy is required to move a 4.00 microcoulomb charge through a potential difference of 36.0 volts? 1.44E-4 J]

18. If 12.0 Joules of work is required to move 3.0 Coulomb of charge between two points in an electric field, what is the potential difference between the two points? [ 4 V]

19. Five coulombs of charge are moved between two points in an electric field where the potential difference between the points is 12 V. How much work is required? [60 J]

20. In an electric field, 0.90 joules of work is required to bring 0.45 coulombs of charge from point A to B. What is the electrical potential difference between A and B?[2V]

21. What is meant by the capacitance of a capacitor? The ratio of the charge on the plates of the capacitor to the potential difference across them. C = Q/V and it has the units of farad.

22. Define the farad. The charge required to increase the potential difference across the plates by 1 V.

23. A capacitor of capacitance 5 µF is connected to a 6 V supply.

a. What charge is stored in the capacitor? [30 µC]

b. A 400E-12 F capacitor carries a charge of 2.5E-8 C. What is the potential difference across the plates of the capacitor? [62.5 V]

24. A capacitor is charged such that there is a charge of +20 mC on the positive plate. What is the charge on the negative plate? [- 20 mC equal and opposite.]

C

4.5 V

25. A 4700 µF capacitor is connected as shown in the circuit diagram. When it is fully charged:

a. What is the charge on the positive plate of the capacitor? [0.021 C]

b. What is the potential difference across the capacitor? [4.5 V]

c. How many additional electrons are on the negative plate? [1.32E 17]