CAIE A-Level Physics 9.3.2 Using V = IR
Practise calculating current, potential difference or resistance with V = IR, interpreting V-I data and applying the relationship at the stated operating point.
- Syllabus
- 2028–2030
- Course
- Physics 9702
- Level
- AS
Practise calculating current, potential difference or resistance with V = IR, interpreting V-I data and applying the relationship at the stated operating point.
A battery of electromotive force (e.m.f.) E and internal resistance r is connected to a variable resistor of resistance R, as shown in Fig. 6.1.

Fig. 6.1
The current in the circuit is I and the potential difference across the variable resistor is V.
The battery stores 9.2 kJ of energy. The variable resistor is adjusted so that V=2.1 V. Use Fig. 6.2 to:
calculate resistance R
R=2.1/0.50=4.2Ω
A1