Units (Magnetism & Electromagnetism)
4 marks · EasyA wire is connected to a battery and a current flows through it. The current in the wire is measured as 2.0 A. The voltage across the wire is 6.0 V.
State the correct units for current and voltage.
Calculate the power supplied to the wire. Give the correct unit 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) Current: ampere (A); Voltage: volt (V)
(b) 12 W
Common mistakes: Writing 'amps/volts' instead of A/V for units; Not stating power in watts
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct unit for current: ampere (A).
B2 (a) · 1 mark · States correct unit for voltage: volt (V).
M1 (b) · 1 mark · Recalls or uses equation: Power = Current x Voltage (P = IV).
A1 (b) · 1 mark · Correct calculation: 2.0 A × 6.0 V = 12 W. States correct unit (Watt/watts/W).
Worked solution
a) The unit for current is the ampere (A). The unit for voltage is the volt (V).
b) Power is calculated using P = IV, so P = 2.0 A × 6.0 V = 12 W.