A 5 Ω resistor and a 15 Ω resistor are connected in series with a power supply. A voltmeter connected across the 15 Ω resistor reads 45 V. What is the voltmeter reading when it is connected across the 5 Ω resistor?
15 V15\text{ V}15 V
30 V30\text{ V}30 V
45 V45\text{ V}45 V
135 V135\text{ V}135 V
136 exam-style questions on CIE IGCSE Physics 4.3 Electric circuits, covering 4.3.1a Circuit diagrams and circuit components, 4.3.2a Series circuits, 4.3.2b Parallel circuits, 4.3.2c Current and potential difference in circuits, 4.3.2d Combined resistance of resistors in parallel, and 4.3.3 Action and use of circuit components. Each one has a worked solution and a mark scheme showing where the marks go.