IB Fields - Electric and Magnetic

page 1


1. Two identical charges q are seperated by a distance r. The charges will repel with a force F.

If the distance between the charges is increased to 2r and both charges increased to 2q, the force will now be

  • A. F/4
  • B. F/2
  • C. F
  • D. 2F

2. An electronvolt is a unit of

  • A. work done
  • B. charge
  • C. voltage
  • D. current

3. Which of these diagrams correctly shows the electric field strength between these two charges?

4. Electric field strength is defined as

  • A. the force per unit charge on a small positive test charge
  • B. the force per unit charge on a small negative test charge
  • C. the force per unit charge on a unit positive charge
  • D. the force per unit charge on a unit negative charge


Four metal spheres P,Q, R and S are arranged in a square as shown. Each one has a charge of q or -q or zero.

5. The electric field at a point in the centre of the square will be zero if
  • A. All charges are positive
  • B. P and Q are positive, R and S are negative
  • C. P and Q are positive, R and S have no charge
  • D. P is positive, Q R and S have no charge

6. A current flows in a metal wire when attached to a cell. Which of the following correctly describes the charge carriers in the wire and their movement?

  Charge carrier sign Moves round the circuit from
A + positive to negative
B - positive to negative
C + negative to positive
D - negative to positive


A 2 mC charge is held between two charged plates. The plates have an electric field of 40 'units' between them.



7. The unit of electric field strength E is

  • A. NC
  • B. NV
  • C. NC-1
  • D. NV-1
8. The force on the charge due to the field will be
  • A. 20N
  • B. 80N
  • C. 0.02N
  • D. 0.08N

9. If the voltage between the 2 plates is 2kV, the work done in moving the charge from plate to plate is

  • A. 1J
  • B. 4J
  • C. 1eV
  • D. 4eV

10. Two metal wires A and B have identical currents flowing in them . Wire A has a smaller cross-sectional area than B. This means wire A must also

  • A. have charge carriers with a larger charge than B
  • B. be longer than B
  • C. have fewer charge carriers per unit volume than B
  • D. have a higher charge drift velocity than B