D.C. circuits — AS & A Level Physics (9702) questions by topic
D.C. circuits questions ask for resistance from a thermistor's I-V graph, e.m.f. comparison using a potentiometer's sliding contact, and current in an LDR-and-fixed-resistor combination, each worth from 1 to 11 marks.
Calculate, deduce and identify lead the command words, joined by state and explain: explain why a current stays constant, or deduce which component's resistance changes with light intensity. 71 real questions from 2023 to 2025 papers are set out here. Submitting worked answers for instant marking flags a reciprocal-resistance formula written the wrong way round, or an LDR current wrongly equated to a fixed resistor's, immediately rather than after the whole paper is marked.
What examiners look for
- A recurring mistake using the parallel-resistor method is writing R = 1/R1 + 1/R2 instead of the correct reciprocal form 1/R = 1/R1 + 1/R2.
- Examiners note even some stronger candidates wrongly assume the current in an LDR equals the current in a separate fixed resistor.
- A common misconception is that increasing light intensity increases LDR resistance; reports stress precision about which resistance, current or potential difference is meant.
- Strong answers sometimes calculate the current in the fixed resistor, apply Kirchhoff's first law to find the LDR current, then find its resistance.
May–June 2025, Paper 11
The diagram shows six identical resistors connected in a circuit. The circuit has nodes P (left), Q (top), R (right), S (bottom). Between P and Q there is one resistor. Between Q…
Answer this question and get it marked →The diagram shows a circuit containing a thermistor, a fixed resistor and a battery connected in series. The graph shows the I–V characteristics of both components (two curves…
Answer this question and get it marked →A cell is connected in series with an ammeter and a variable resistor. A voltmeter is used to measure the p.d. across the variable resistor. The resistance of the variable…
Answer this question and get it marked →May–June 2025, Paper 12
The diagram shows a cell of internal resistance 1.0R connected to a variable resistor. When the variable resistor has an initial resistance of 2.0R, the current in the cell is I₁…
Answer this question and get it marked →The diagram shows a four-terminal box connected to a battery and two ammeters. The currents in the two ammeters are identical. Which circuit, within the box, gives this result?
Answer this question and get it marked →Each of Kirchhoff's two laws presumes that some quantity is conserved. Which row states Kirchhoff's first law and names the quantity that is conserved? statement quantity --- ---…
Answer this question and get it marked →May–June 2025, Paper 13
A circuit contains two resistors of resistance R and two resistors of resistance 3R. A voltmeter is connected across part of the circuit. What is the reading on the voltmeter? A…
Answer this question and get it marked →A battery of e.m.f. E and internal resistance r is connected to a variable resistor. As the resistance of the variable resistor is increased, the current I in the circuit…
Answer this question and get it marked →A device of resistance 20 Ω is connected in series with a variable resistor. The supply voltage is 16 V. The power dissipated in the device is 4.0 W. What is the resistance of the…
Answer this question and get it marked →May–June 2025, Paper 14
A cell of constant electromotive force (e.m.f.) and negligible internal resistance is separately connected into four different circuits. In which circuit does the power dissipated…
Answer this question and get it marked →The sum of the electrical currents into a point in a circuit is equal to the sum of the currents out of the point. Which statement is correct? A This is Kirchhoff's first law,…
Answer this question and get it marked →A battery of electromotive force (e.m.f.) 6.0 V and negligible internal resistance is connected to three resistors as shown. The circuit has a 30 Ω resistor in series with the…
Answer this question and get it marked →A potentiometer circuit may be used to determine the unknown electromotive force (e.m.f.) E of a cell. The circuit diagrams shown include a battery of known e.m.f. and negligible…
Answer this question and get it marked →May–June 2025, Paper 21
A nichrome wire X of length 45 cm and cross-sectional area 4.7 × 10⁻⁷ m² is connected into a circuit with a cell. The resistance of X is 1.1 Ω. The cell has electromotive force…
Answer this question and get it marked →May–June 2025, Paper 24
A potentiometer circuit consists of a wire XY of length 2.00 m and resistance 8.0 Ω. A battery of e.m.f. 6.0 V and negligible internal resistance is connected in series with a…
Answer this question and get it marked →May–June 2024, Paper 11
Which circuit results in output voltage Vout increasing with increasing temperature? The circuits each contain a cell, a fixed resistor and a thermistor arranged as a potential…
Answer this question and get it marked →Four resistors, each of resistance R, are connected as shown. Between terminals X and Y there is one resistor R directly across X–Y, and a series combination of three resistors R…
Answer this question and get it marked →A cell with internal resistance is connected to a variable resistor R as shown. The resistance of R is gradually decreased. How do the current I and the terminal potential…
Answer this question and get it marked →The diagram shows a circuit with a cell and three resistors with resistances R₁, R₂ and R₃. The cell has negligible internal resistance. R₁ and R₂ are in series with each other,…
Answer this question and get it marked →May–June 2024, Paper 12
The diagram shows a cell of negligible internal resistance connected to a switch and two resistors of resistances R and 2R. The resistor R is in one branch with ammeter X; the…
Answer this question and get it marked →Which description of Kirchhoff's first law is correct? A It considers the currents at a junction in a circuit and is a consequence of the conservation of charge. B It considers…
Answer this question and get it marked →Two resistors of resistances r and R are connected in parallel. The value of r is less than that of R. Which statement about the combined resistance of the two resistors is…
Answer this question and get it marked →The diagram shows four identical resistors connected in a circuit. Resistor A is in series with the cell; resistors B and C are in series with each other, and that combination is…
Answer this question and get it marked →May–June 2024, Paper 13
A student builds the circuit shown. All the lamps are identical. Lamp D is in series with the cell. Lamp A is in parallel with the series combination of lamps B and C. Which lamp…
Answer this question and get it marked →A circuit needs to be completed by connecting two resistors between points X and Y, as shown. The resistors can be connected in series or in parallel with each other. Which…
Answer this question and get it marked →The diagram shows a circuit that includes a cell with internal resistance. Current I₁ flows from the cell; current I₂ flows through a resistor branch. A switch in a separate…
Answer this question and get it marked →The diagram shows a circuit consisting of a cell and three resistors R₁, R₂ and R₃. R₁ and R₂ are in series with each other; that combination is in parallel with R₃. The cell has…
Answer this question and get it marked →The diagram shows a potentiometer circuit used to compare the electromotive forces (e.m.f.), E₁ and E₂, of two cells. XY is a uniform resistance wire. The fixed resistor has…
Answer this question and get it marked →May–June 2024, Paper 21
May–June 2024, Paper 22
May–June 2024, Paper 23
October–November 2024, Paper 11
Kirchhoff's second law is a consequence of a basic principle. What is this principle? A The charge flowing in an electric circuit is conserved. B The energy in an electric circuit…
Answer this question and get it marked →The diagram shows a circuit with a light-dependent resistor (LDR). A 12 V supply is connected across two parallel branches. One branch has a 10 kohm resistor in series with a 30…
Answer this question and get it marked →A cell with internal resistance is connected to a light-dependent resistor (LDR), a fixed resistor and a voltmeter, as shown. The voltmeter is connected across the fixed resistor.…
Answer this question and get it marked →The circuit shown contains a cell with negligible internal resistance connected to a component X. The energy transferred per unit charge in driving charge around the complete…
Answer this question and get it marked →In the circuits shown, the batteries are identical and all have negligible internal resistance. All of the resistors have the same resistance. The diodes have zero resistance when…
Answer this question and get it marked →A potentiometer circuit is used to determine the electromotive force (e.m.f.) E of a cell. The circuit includes a second cell of e.m.f. 1.5 V and internal resistance 0.50 ohm that…
Answer this question and get it marked →October–November 2024, Paper 12
Each of Kirchhoff's laws is a statement based on the conservation of a physical quantity. Which quantity is conserved in each law? Kirchhoff's first law Kirchhoff's second law ---…
Answer this question and get it marked →A cell with electromotive force (e.m.f.) 1.50 V delivers a current of 0.26 A to a resistor of resistance 5.0 ohm connected between its terminals. What is the internal resistance…
Answer this question and get it marked →October–November 2024, Paper 13
The diagram shows part of a circuit that uses a potentiometer wire to measure a potential difference (p.d.) in an external circuit. The potentiometer wire XZ has length L1. It is…
Answer this question and get it marked →The diagram shows a circuit containing a cell with internal resistance, a switch, a lamp and a voltmeter connected across the lamp. Which statement about the circuit is not…
Answer this question and get it marked →A circuit contains a battery of electromotive force E and internal resistance r connected to two resistors each of resistance 2.5 ohm. The resistors are connected in parallel as…
Answer this question and get it marked →October–November 2024, Paper 21
Fig. 7.1 shows two resistors connected in series with a cell of electromotive force (e.m.f.) 1.50 V and internal resistance 0.28 ohm. One of the resistors has resistance 1.0 ohm.…
Answer this question and get it marked →February–March 2023, Paper 12
A cell has a constant electromotive force. A variable resistor is connected between the terminals of the cell. The resistance of the variable resistor is decreased. Which…
Answer this question and get it marked →Kirchhoff's two laws for electric circuits can be derived by using conservation laws. On which conservation laws do Kirchhoff's laws depend? Kirchhoff's first law Kirchhoff's…
Answer this question and get it marked →A battery of electromotive force (e.m.f.) 10 V and internal resistance r is connected to three resistors of resistances R, 2.0 ohm and 15 ohm, as shown. A current of 0.45 A is in…
Answer this question and get it marked →A battery of negligible internal resistance is connected in series with a thermistor and a fixed resistor of resistance 12.0 kohm, as shown (a potential divider). The table shows…
Answer this question and get it marked →May–June 2023, Paper 11
A battery with internal resistance is connected to a fixed resistor, an ammeter and a voltmeter, as shown. The battery is replaced by a different battery that has the same…
Answer this question and get it marked →Four potential divider circuits each consist of a battery of e.m.f. 9 V and negligible internal resistance connected to a combination of resistors. Each of the resistors in the…
Answer this question and get it marked →A voltmeter is connected into a circuit with the polarity shown. A 3 V cell drives current through a potentiometer wire PQ; a second 3 V cell is connected via the voltmeter. The…
Answer this question and get it marked →May–June 2023, Paper 12
A student assembles the circuit shown. A cell is connected to lamp 1 in series with a branch containing diodes, and lamp 2; one diode is in series with lamp 1's branch and two…
Answer this question and get it marked →Kirchhoff's first law is a consequence of the conservation of which quantity? A charge B energy C momentum D potential difference
Answer this question and get it marked →Three identical cells each have electromotive force (e.m.f.) E and negligible internal resistance. The cells are connected to three identical resistors, each of resistance R, in a…
Answer this question and get it marked →In the potentiometer circuit shown, the reading on the ammeter is zero. A power supply drives current through a uniform metal wire; a fixed resistor and a light-dependent resistor…
Answer this question and get it marked →May–June 2023, Paper 13
Two resistors of resistances R and 2R are connected in parallel with a battery of e.m.f. 12 V and negligible internal resistance. The total power dissipated by the two resistors…
Answer this question and get it marked →A battery with internal resistance is connected to a parallel arrangement of two resistors and a switch S, as shown. Initially, switch S is open. What happens to the voltmeter and…
Answer this question and get it marked →Kirchhoff's first law states that the sum of the currents entering a junction in a circuit is equal to the sum of the currents leaving it. The law is based on the conservation of…
Answer this question and get it marked →A potentiometer circuit is used to investigate the e.m.f. of a cell X. The e.m.f. of cell X is known to be approximately 0.50 V. The driver cell has negligible internal resistance…
Answer this question and get it marked →May–June 2023, Paper 21
A battery of electromotive force (e.m.f.) 9.6 V and negligible internal resistance is connected in series with two fixed resistors and a thermistor, as shown in Fig. 7.1. The…
Answer this question and get it marked →May–June 2023, Paper 22
A battery of electromotive force (e.m.f.) 9.0 V and negligible internal resistance is connected to a light-dependent resistor (LDR) and a fixed resistor, as shown in Fig. 7.1. The…
Answer this question and get it marked →October–November 2023, Paper 11
Kirchhoff's first and second laws are a consequence of the conservation of which quantities? A charge and energy B charge and resistance C mass and energy D mass and resistance
Answer this question and get it marked →A circuit contains a cell of electromotive force E and internal resistance r connected to a resistor of resistance R. The current in the circuit is I. Which equation is correct? A…
Answer this question and get it marked →A potential divider consists of two resistors of resistances R1 and R2 connected in series across a source of potential difference (p.d.) Vin. The p.d. across R1 is Vout. Which…
Answer this question and get it marked →October–November 2023, Paper 12
A student sets up a circuit. The circuit diagram shows how the positive and negative terminals of a voltmeter are connected to the circuit. The circuit contains a thermistor and a…
Answer this question and get it marked →Kirchhoff's first law is a consequence of the conservation of which physical quantity? A charge B energy C linear momentum D potential difference
Answer this question and get it marked →In the circuit shown, a battery of negligible internal resistance is connected in series with a pair of fixed resistors R1 (60 ohm) and R2 (20 ohm) across a 6.0 V supply. The…
Answer this question and get it marked →October–November 2023, Paper 13
A battery of electromotive force (e.m.f.) 12 V and negligible internal resistance is connected to a fixed resistor of resistance 40 ohm and a thermistor of resistance RT in…
Answer this question and get it marked →A cell of electromotive force (e.m.f.) 3.0 V and internal resistance 0.50 ohm is connected to a variable resistor, a voltmeter and an ammeter. The resistance of the variable…
Answer this question and get it marked →Three resistors, R1, R2 and R3, are connected in parallel to a cell. The currents in the resistors are I1, I2 and I3. The potential differences across the resistors are V1, V2 and…
Answer this question and get it marked →A potentiometer and a driver cell of electromotive force (e.m.f.) E are used to measure the e.m.f. of a new cell. A sliding contact at P is moved along a resistance wire QR until…
Answer this question and get it marked →October–November 2023, Paper 21
A battery is connected in a circuit with a light-dependent resistor (LDR), two fixed resistors and a voltmeter, as shown in Fig. 6.1. The battery has an electromotive force…
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