1. A test charge of -2 x 10^-8 C experiences a force of 0.06 N when placed in an electric field. What is the electric field intensity? If the test charge has mass of 5 x 10^-22 kg, what acceleration does it experience due to this force? Ans: 3 x 10⁶N/C; 1.2 x 10²⁰ m/s^s
2. A test charge of +5 x 10^-4 C is in an electric field which exerts a force of 2.5 x 10^-4N upon it. What is the strength of the electric field? Ans: 0.5 N/C
3. A test charge of +80 mC is placed in a 50 N/C field. What force does it experience? Ans: 0.004 N
4. A +4.9 mC charge produces an electric field of 3.6 x 10⁴ N/C upon a positive test charge. How far away is the charge? Ans: 1.11 m
5. A 19 mC charged sphere produces a 1.7 x 10 ³ N/C upon a 0.5 mC test charge. What force is the charge subjected to? How far away is the test charge from the sphere? Ans: 0.00085 N; 10.03 m
6. The electric field intensity between two parallel, charged plates is 8000 N/C. The plates are 0.05 m apart. What potential difference exists between the plates? What work is done on a proton (mass = 1.67 x 10^-27 kg) to move it from the negative to the positive plate? What force acts on the proton due to the electric field between the two plates? If the proton is released rom rest at the positive plate, what acceleration does it experience? What is its speed the instant before striking the negative plate? Ans: 400 V; 6.4 x 10^-17 J; 1.28 x 10^-15 N; 7.66 x 10¹¹ m/s²; 2.77 x 10⁵ m/s
7. A spark will jump across dry air when the electric field is larger than 1 x 10⁶ N/C. If two parallel plates have a potential difference of 5000 V, how far apart must they be to prevent a spark from jumping across them? Ans: 0.005 m
8. What work is done on a 5 C charge when its electric potential is increased by 1.5 V? Ans: 7.5 J
9. A charge of 50 C is raised in potential by 110 V. What work is done in raising the potential of the charge? Ans: 5500 J

1. An oil drop carries a charge of 5 electrons and is balanced in a field of 4.7 x 10⁴ N/C. What is the drop's weight? Ans: 3.76 x 10^-14 N
2. A negatively charged oil drop weighs 8.5 x 10^-15 N. The drop is suspended in an electric field of 5300 N/C. What is the drop's charge? How many excess electrons does it carry? Ans: 1.6 x 10 ^-18 C; 10 electrons
3. What is the charge on a 6mF capacitor with a potential difference of 0.60 V? Ans: 3.6 mC
4. A capacitor has a charge of 3 mC and a potential difference of 45 V. What is its capacitance? Ans: 0.067 mF
5. A 0.002 F capacitor has a 6 V potential difference across it. How much energy does it store? Ans: 0.036 J
6. A +26 C charged sphere is touched to a -19 C charged sphere and then removed. What charge remains on each? Ans: +3.5 C

Electric Field, Potential, and Capacitors Notes

Electric Field, Potential, and Capacitors Sample Problems