Oxford AQA International A-level · Physics (9630)
4 multiple-choice questions marked as you go, and 3 written questions with worked solutions. All on Electromotive force and internal resistance.
A cell has an electromotive force (emf) of \( \mathcal{E} \) and an internal resistance \( r \). When connected to an external circuit, it delivers a current \( I \). Which of the following statements correctly describes the terminal potential difference \( V \) across the cell?
A power supply has an EMF of \( 12.0 \text{ V} \) and an internal resistance of \( 0.50 \text{ } \Omega \). It is connected to an external resistor of resistance \( R \). If the current flowing through the circuit is \( 2.0 \text{ A} \), what is the terminal potential difference across the power supply?
A cell with EMF \( 1.5 \text{ V} \) and internal resistance \( 0.20 \text{ } \Omega \) is connected in series with a \( 2.8 \text{ } \Omega \) resistor and a parallel combination of two resistors, \( 4.0 \text{ } \Omega \) and \( 6.0 \text{ } \Omega \). Calculate the current flowing through the \( 4.0 \text{ } \Omega \) resistor.
The graph shows the terminal potential difference \( V \) across a cell varying with the current \( I \) supplied by the cell.
The line intercepts the V-axis at \( 6.0 \text{ V} \) and the I-axis at \( 3.0 \text{ A} \). What are the EMF and internal resistance of the cell?
A cell has an EMF of \(1.5 \, V\) and an internal resistance of \(0.5 \, \Omega\). When it is connected to an external resistor, the terminal potential difference is \(1.2 \, V\). Calculate the current flowing through the circuit and the resistance of the external resistor.
Write your answer out first, then check it against the worked solution.
A student investigates the terminal potential difference (PD) of a cell as the current drawn from it varies. The following data are collected:
Current \(I\) / A | Terminal PD \(V\) / V
---|---
0.10 | 1.45
0.20 | 1.40
0.30 | 1.35
0.40 | 1.30
0.50 | 1.25
(a) On a piece of graph paper, plot a graph of terminal PD \(V\) (y-axis) against current \(I\) (x-axis). Draw a best-fit straight line.
(b) Use your graph to determine the electromotive force (emf) of the cell.
(c) Use your graph to determine the internal resistance of the cell.
(d) Explain why the terminal PD decreases as the current increases.
Write your answer out first, then check it against the worked solution.
A cell has an electromotive force (emf) of \(1.5 \, \text{V}\) and an internal resistance of \(0.50 \, \Omega\). It is connected to an external resistor \(R_L = 2.5 \, \Omega\).
(a) Calculate the current flowing through the circuit.
(b) Determine the terminal potential difference (PD) across the external resistor.
(c) Calculate the power dissipated by the internal resistance of the cell.
(d) If a second identical external resistor of \(2.5 \, \Omega\) is connected in parallel with the first external resistor, calculate the new current drawn from the cell.
Write your answer out first, then check it against the worked solution.
* The content provided by thinka is generated by AI and may not always be accurate or up-to-date. Please use it as a supplementary resource and verify with official materials.
This page can show you how a good answer looks. It cannot tell you what your answer was missing. thinka marks your written work against the real mark scheme in about 15 seconds.
Want more questions like these? Get a fresh set on this topic, marked as you go.
Practise More