CIE iGCSE Co-Ordinated Science P4.2.3 Voltage (electromotive force and potential difference) Exam Style Questions Paper 1
▶️ Answer/Explanation
Current is measured in amperes and resistance is measured in ohms, not volts.
Electromotive force (e.m.f.) describes the energy supplied per unit charge by a source, measured in volts.
Potential difference (p.d.) describes energy transferred per unit charge across a component, also measured in volts.
✅ Answer: (B)
Electromotive force (e.m.f.) describes the energy supplied per unit charge by a source, measured in volts.
Potential difference (p.d.) describes energy transferred per unit charge across a component, also measured in volts.
✅ Answer: (B)
▶️ Answer/Explanation
Electromotive force (e.m.f.) is measured in volts (V), not newtons — eliminating options A and B immediately; a voltmeter has very high resistance and must always be connected in parallel across the component (not in series) to measure voltage without disrupting the circuit.
Connecting a voltmeter in series would drastically reduce current flow and give an incorrect reading; parallel connection ensures it measures the full potential difference across the cell terminals.
✅ Answer: (C)
Connecting a voltmeter in series would drastically reduce current flow and give an incorrect reading; parallel connection ensures it measures the full potential difference across the cell terminals.
✅ Answer: (C)
▶️ Answer/Explanation
Current is measured in amperes and resistance is measured in ohms, so neither shares a unit with potential difference.
Potential difference (p.d.) and electromotive force (e.m.f.) are both types of voltage, since e.m.f. is the voltage of the source and p.d. is the voltage across a component.
Because both describe a form of voltage, they are both measured in volts (V), the same unit.
✅ Answer: (C)
Potential difference (p.d.) and electromotive force (e.m.f.) are both types of voltage, since e.m.f. is the voltage of the source and p.d. is the voltage across a component.
Because both describe a form of voltage, they are both measured in volts (V), the same unit.
✅ Answer: (C)
Question
The electromotive force (e.m.f.) of a battery is 2.0 V. Which statement is correct?
A. The battery supplies 0.50 J of energy for every 1.0 C of charge driven around the circuit.
B. The battery supplies 0.50 J of energy for every 2.0 C of charge driven around the circuit.
C. The battery supplies 2.0 J of energy for every 1.0 C of charge driven around the circuit.
D. The battery supplies 2.0 J of energy for every 2.0 C of charge driven around the circuit.
▶️Answer/Explanation
Answer: C
Explanation: The electromotive force (e.m.f.) is the energy supplied per unit charge. If the e.m.f. is 2.0 V, it means the battery supplies 2.0 J of energy for every 1.0 C of charge. Therefore, the correct answer is C.