Coulomb's Law

1. Two small charged balls feel a repulsive force of 0.2N when they are separated by a distance of 1.0m. The balls are then moved to a distance of 0.6m apart. What is the new force?

1. 0.56 N

2. 0.2 N

3. 0.33 N

4. 0.12 N

2. Three +1 micro-C charges are placed at positions x=1 m, x=2 m, and x=10 m. What is the net electrostatic force (magnitude and direction) on the charge at position x=2 m?

1. +8.9 mN

2. -9.9 mN

3. -900 N

4. +9.1 mN

Electric Fields

1. A small pith ball has a charge of 0.001 C. What is the electric field 0.3 m from the ball? Remember that k=8.988x10^9 N m^2/C^2.

1. 0.01 N/C 2. 10^8 N/C

3. 3x10^7 N/C

4. 3.3x10^-3 N/C

2. Ball A has a charge of 1 C, while ball B has a charge of -2 C.

2. The balls are placed 2 m apart and held in place. What is the net electric field at a point half-way between them?

1. 2.7x10^10 N/C toward ball B

2. 9x10^9 N/C toward ball B

3. 9x10^9 N/C toward ball A

4. 2.7x10^10 N/C toward ball A

Capacitance and Capacitors

1. A parallel plate capacitor has area 1 m^2 with the plates separated by 0.1 mm. What is the capacitance of this capacitor?

1. 8.85x10^-8 F

2. 8.85x10^-11 F

3. 8.85x10^-12 F

4. 10,000 F

2. A parallel plate capacitor has area 1 m^2 with the plates separated by 0.1 mm. The plates are connected to a 12V battery. What is the charge on the plates?

1. 1.06 nC

2. 1.06x10^-11 C

3. 120,000 C

4. 1.06 micro-C

3. A parallel plate capacitor has area 1 m^2 with the plates separated by 0.1 mm. It is connected to a 12 V battery. What is the electric field between the plates?

1. 1.2 N/C

2. 120,000 N/C

3. 12 N/C

4. 120 N/C

Capacitors, Dielectrics, and Energy

1. A parallel plate capacitor has area 1 m^2 with the plates separated by 0.1 mm. What is the capacitance of this capacitor?

1. 8.85x10^-8 F

2. 8.85x10^-11 F

3. 8.85x10^-12 F

4. 10,000 F

2. A capacitor has area 1m^2 with plate separation 0.1mm with material with dielectric constant 10^4 between the plates. What charge will it hold when connected to a 12V battery?

1. 1.06x10^-15 C

2. 1.2 MC

3. 10.6 mC

4. 1.06x10^-9 C

3. A capacitor has area 1m^2 with plate separation 0.1mm with material with dielectric constant 10^4 between the plates. What energy will be stored when connected to a 12 V battery?

1. 6.37 mJ

2. 6.37 micro-J

3. 63.7 mJ

4. 7.2 GJ

Capacitors in Circuits

1. A 1 mF and a 3 mF capacitor are wired in series to a 10 V battery. What is the equivalent capacitance of the circuit?

1. 2 mF

2. 4 mF

3. 1.33 mF

4. 0.75 mF

2. A 1 mF and a 3 mF capacitor are wired in series to a 10 V battery. What is the charge on the 3 mF capacitor?

1. 7.5 mC

2. 13.3 mC

3. 40 mC

4. 20 mC

3. A 1 mF and a 3 mF capacitor are wired in parallel to a 10 V battery. What is the equivalent capacitance of the circuit?

1. 2 mF

2. 1.33 mF

3. 0.75 mF

4. 4 mF

4. A 1 mF and a 3 mF capacitor are wired in parallel to a 10 V battery. What is the charge on the 3 mF capacitor?

1. 13.3 mC

2. 7.5 mC

3. 40 mC

4. 30 mC

Resistance, Current, and Ohm's Law

1. In a lightening strike lasting 45 ms, a total charge of 350 C is transferred to the ground. What is the average current?

1. 7.8 A

2. 7800 A

3. 1600 A

4. 0 A

2. A 12V battery is connected to a 100 Ohm resistor. What current flows through the resistor?

1. 0.12 mA

2. 12 mA

3. 1.2 mA

4. 120 mA

Resistors in Series and Parallel

1. The equivalent resistance of a 120 k and a 140 k resistor wired in parallel is:

1. 20 k-Ohm

2. 65 k-Ohm

3. 260 k-Ohm

4. 0.15 k-Ohm

2. A 34 Ohm and 45 Ohm resistor are wired in series and connected to a 7.5 V battery. How much current flows in the circuit?

1. 2.6 A

2. 390 mA

3. 95 mA

4. 10.5 A