ALTERNATING CURRENT AND DIRECT CURRENT
3 marks · EasyA torch uses a battery to provide electricity to a bulb.
State whether the current from the battery is alternating current (a.c.) or direct current (d.c.).
Give a reason for your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Direct current (d.c.)
(b) A battery supplies current in one direction only, and the value does not change direction like in alternating current.
Common mistakes: Confusing mains and battery
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies battery current as direct current (d.c.).
B2 (b) · 1 mark · States reason: battery provides current in only one direction / has constant direction.
B3 (b) · 1 mark · Further detail (e.g. d.c. value does not alternate; a.c. changes direction).
Worked solution
a) The current from the battery is direct current (d.c.).
b) This is because the battery provides a constant voltage that pushes charges in one direction only, so the current flows in a straight line (d.c.). Alternating current (a.c.) reverses direction, but a battery does not do this.