## Thursday, 18 September 2014

### ELECTROMAGNETSM

1.Which one of the following is a correct definition of electric potential difference between two points?
A.      The power to move a small positive charge between the two points.
B.      The work done to move a small positive charge between the two points.
C.      The power per unit charge to move a small positive charge between the two points.
D.      The work done per unit charge to move a small positive charge between the two points.

2.Electric field strength is defined as
A.      the force exerted on a test charge.
B.      the force per unit positive charge.
C.      the force per unit charge.
D.      the force per unit charge exerted on a positive test charge.

3.A magnetic force acts on an electric charge in a magnetic field when
A.      the charge is not moving.
B.      the charge moves in the direction of the magnetic field.
C.      the charge moves in the opposite direction to the magnetic field.
D.      the charge moves at right angles to the lines of the magnetic field.

4.A conductor of constant resistance dissipates 6.0 W of power when the potential difference across it is 12 V. The power that will be dissipated in this conductor when the potential difference across it is 24 V is
A.      6.0 W.
B.      12 W.
C.      24 W.
D.      48 W.
5.Which of the following is the correct value of the electronvolt, measured in SI Units?
A.      1.6 ´ 10–19 N
B.      1.6 ´ 10–19 J
C.      9.1 ´ 10–31 N
D.      9.1 ´ 10–31 J
6.The work done on a positive point charge of magnitude 3.0 nC as it is moved at constant speed from one point to another is 12 nJ. The potential difference between the two points is
A.      0.0 V.
B.      0.25 V.
C.      4.0 V.
D.        36 V