10 minutes maximum! Can you do it in 5?

 1. A current of 2 amps flows along a conductor. Which of these statements correctly describes this current?

• A. 2 coulombs of charge flows past one point.
• B. 2 coulombs of charge flows past one point per second.
• C. 2 joules of energy is transferred.
• D. 2 joules of energy is transferred per second.

2. Which of these answers best describes the name and polarity of the charge carrier in a metal conductor?

3&4. A cell is connected to a motor.

A charge of 12 coulombs flows through the motor in 3 seconds. The voltage of the cell is 6 V, and it has a negligible internal resistance.

3. What is the current flowing in the circuit?

• A. 0.25 A
• B. 2 A
• C. 4 A
• D. 36 A

4. What work has been done by the cell in this time?

• A. 6 J
• B. 36 J
• C. 48 J
• D. 72 J

5. An electronvolt is a unit of...

• A. energy
• B. potential difference
• C. power
• D. electric field strength

Two charges +Q are separated by a distance r. There is a repulsion force F acting between the 2 charges as shown:

6. What is the size of the force if the charges are moved to a distance of ½ r?

• A. ¼ F
• B. ½ F
• C. 2 F
• D. 4 F

7. Which of these changes to the diagram in Q5 would increase the force to 6F?

• A. Increase the original distance to 3r.
• B. Decrease the original distance by a factor of 3.
• C. Keep the original distance, but increase both charges to + 3 Q.
• D. Keep the original distance, but increase both charges to + √6 Q.

8. Two copper rods, P and Q, have identical currents flowing through them. P has a smaller diameter than Q.

Which of these answers best describes the differences between values of 'n' and 'v' in both rods, using the formula I = nAvq?

9. At which point in this diagram is the electric field due to the 2 charges equal to zero?

10. The sign of the right hand charge has now been reversed. At which point in this diagram is the electric field zero?