Series and parallel circuits

Three identical cells are linked in parallel to a resistor. What advantage is gained by using three cells in parallel instead of one cell?

May/June 2015

The diagram illustrates three resistors connected in parallel. What is the total resistance?

May/June 2015

A pair of resistors with resistances $30\,\Omega$ and $60\,\Omega$ are connected in parallel. The current through the $30\,\Omega$ resistor is $0.60\,\text{A}$. What potential difference is across the $60\,\Omega$ resistor?

May/June 2015

The diagram contains three resistors arranged in series and joined to a battery. A voltmeter is connected across each resistor, and two of the voltages are given. What is the potential difference (p.d.) across the resistor $R$?

May/June 2015

Fig. 6.1 illustrates a circuit made up of a resistor linked to a 6.0 V power supply and a lamp L. The resistor has a resistance of $60\,\Omega$. The lamp is marked 6.0 V, 0.90 W.

May/June 2015

The cells, lamps and resistors in the circuits are the same. In which circuit is the lamp brightest?

May/June 2016

Figure 8.1 illustrates a circuit containing a battery, one fixed resistor with resistance $1000\,\Omega$, and a variable resistor R.

May/June 2016

For what reason are batteries sometimes constructed from several identical cells connected in parallel?

May/June 2017

A thermistor and a light-dependent resistor (LDR) are joined in series. A potential difference (p.d.) of $6.0\,\text{V}$ is applied across the pair, as shown. The thermistor has a resistance of $6000\,\Omega$ in a cold room and $1000\,\Omega$ in a warm room. The LDR has a resistance of $2000\,\Omega$ in dim light and $500\,\Omega$ in bright light. Under which conditions is the p.d. across the LDR equal to $2.0\,\text{V}$?

May/June 2017

Fig. 5.1 depicts a circuit made from three resistors.

May/June 2017

A student studies a series circuit that contains two different lamps P and Q. For full brightness, both lamps require a working voltage of 2.5 V. She assembles the circuit shown in Fig. 2.1. The student then connects a voltmeter into the circuit to measure the potential difference (p.d.) across lamp P.

May/June 2017

In the circuit diagram, a variable resistor $R$ is connected in parallel with the lower section of a potential divider. The resistance of $R$ rises. What effect does this have on the two voltmeter readings?

May/June 2018

A teacher is using the circuit diagram shown. The identical lamps X and Y are connected to a low voltage a.c. power supply through high resistance transmission wires. Both lamps are switched on. Lamp X is then switched off. Lamp Y remains switched on. What happens to the voltage and the power supplied to lamp Y?

May/June 2019

Two lamps, P and Q, are joined to a battery with electromotive force (e.m.f.) $6.0\,\text{V}$ and an ammeter, as shown in Fig. 6.1. Lamp P has a resistance of $15\,\Omega$. The ammeter gives a reading of $0.65\,\text{A}$.

May/June 2019

Four circuits are shown in the diagrams. In each circuit, there are three $100\,\Omega$ resistors. Which circuit has the lowest total resistance?

May/June 2022

The diagram illustrates an electric circuit. Which lamps are lit when switch $S_1$ is closed and $S_2$ is open?

May/June 2022

Fig. 5.1 shows a student connecting a battery, thermistor X and resistor Y in parallel. The e.m.f. of the battery is $E$. The current in X is $I$. The resistance of Y is larger than the resistance of X.

May/June 2022

A student carries out an investigation into the resistance of two resistors. Fig. 2.1 illustrates the apparatus used to determine the current $I$ through resistor X and the potential difference $V$ across it.

May/June 2022

Three students each give one effect of connecting lamps in parallel instead of in series. Which students are correct?

May/June 2023

Three identical cells are connected in parallel to a resistor. Why is it better to use three cells in parallel instead of one cell?

May/June 2023

A student possesses three $15\,\Omega$ resistors. She joins the resistors in a variety of different arrangements. What is the lowest resistance and what is the highest resistance of the arrangements that the student can make?

May/June 2023

Fig. 3.1 presents a circuit that includes three resistors, a 12 V power supply and an ammeter.

May/June 2023

The diagrams depict five electrical circuits. Every resistor shown is identical. Which circuits have the same resistance?

May/June 2024

The graph illustrates the way the resistance of a thermistor changes with temperature. The thermistor is at a temperature of $10\,^{\circ}\text{C}$ and is linked in series with a fixed resistor whose resistance is $20\,\Omega$. What is the total resistance of the two components together?

May/June 2025

Every resistor in the circuit diagram has a resistance of $6.0\,\Omega$. What is the total resistance of the circuit?

May/June 2025

As shown, two resistors joined in series form a potential divider. Their resistances are $R_1$ and $R_2$, and the potential differences across them are $V_1$ and $V_2$ respectively. Which expression is equal to $\frac{V_1}{V_2}$?

May/June 2025

Three $10\,\Omega$ resistors are joined together to make networks X, Y and Z. In what sequence do the networks rank by total resistance, from the smallest to the largest?

Oct/Nov 2015

A power supply is connected to four resistors that have different resistances, as shown. The currents through the four resistors are $I_1$, $I_2$, $I_3$ and $I_4$. Which equation is correct?

Oct/Nov 2015

Which part of the circuit includes a potential divider?

Oct/Nov 2015

In the circuit diagram, all the lamps are identical. Lamp P glows at normal brightness. Switch Y is closed, and the lamps switch on. Which row shows the brightness of the lamps?

Oct/Nov 2015

An $18\,\text{V}$ power supply is connected to three resistors, as shown. What potential difference is across the $2.0\,\Omega$ resistor?

Oct/Nov 2015

In the circuit diagram shown, every lamp is identical. Lamp P shines at normal brightness. Switch Y is closed and the lamps illuminate. Which row shows the brightness of the lamps?

Oct/Nov 2015

Resistors with different resistances are linked to a power supply in either a parallel circuit or a series circuit. Which statement is correct?

Oct/Nov 2016

A battery is connected in series with a thermistor and a resistor whose resistance remains constant. A voltmeter is placed in parallel across the resistor. As the temperature decreases, what changes are correct?

Oct/Nov 2016

Fig. 11.1 shows a negatively charged rod positioned near an uncharged metal sphere mounted on an insulating stand.

Oct/Nov 2017

A circuit containing an ammeter, a light-dependent resistor (LDR) and a 1800 Ω fixed resistor is powered by a 4.5 V battery. Fig. 7.1 shows the circuit diagram.

Oct/Nov 2017

Three matching resistors are connected in series to a cell. Voltmeter Q gives a reading of $8.0\,\text{V}$. What value does voltmeter P show, and what is the e.m.f. of the cell?

Oct/Nov 2018

The diagram illustrates three $6.0\,\Omega$ resistors connected so that different total resistances are obtained. What is the difference between the smallest total resistance and the largest total resistance?

Oct/Nov 2018

A power supply is used to connect resistors with different resistances in either a parallel circuit or a series circuit. Which statement is correct?

Oct/Nov 2019

A power supply and three resistors are connected to an ammeter. Which arrangement of the resistors produces the greatest ammeter reading?

Oct/Nov 2019

Resistors with different resistance values are connected to a power supply in either a parallel circuit or a series circuit. Which statement is correct?

Oct/Nov 2019

The circuit contains an ammeter, three resistors and a power supply. Which resistor arrangement produces the largest ammeter reading?

Oct/Nov 2019

A hotplate on an electric cooker contains two identical resistors. The switch can be set to three positions. position 1: The two resistors are joined in series to the mains supply. position 2: The two resistors are joined in parallel to the mains supply. position 3: Only one resistor is joined to the mains supply. Which positions match the low, medium and high power settings?

Oct/Nov 2019

For the circuit illustrated, the resistance of resistor Y is four times the resistance of resistor X. What is the difference $V_Y - V_X$ between the voltages indicated by the voltmeters?

Oct/Nov 2020

A pair of identical resistors are joined in parallel and the combined resistance is $4.0\,\Omega$. What is the combined resistance if those same two resistors are instead connected in series?

Oct/Nov 2020

Three lamps that are all identical and three ammeters are arranged as illustrated. The ammeter readings are $I_1$, $I_2$ and $I_3$. In what way are the readings connected?

Oct/Nov 2020

A thermistor and a light-dependent resistor (LDR) are joined in series. A potential difference (p.d.) of $6.0\,\text{V}$ is applied across the pair, as shown. The thermistor’s resistance is $6000\,\Omega$ in a cold room and $1000\,\Omega$ in a warm room. The LDR’s resistance is $2000\,\Omega$ in dim light and $500\,\Omega$ in bright light. In which situation is the p.d. across the LDR equal to $2.0\,\text{V}$?

Oct/Nov 2020

Three identical lamps and three ammeters are arranged as shown. The ammeter readings are $I_1$, $I_2$ and $I_3$. What is the relationship between these readings?

Oct/Nov 2020

A thermistor and a light-dependent resistor (LDR) are linked in series. A potential difference (p.d.) of $6.0\,\text{V}$ is applied across the pair, as illustrated. The thermistor's resistance is $6000\,\Omega$ in a cold room and $1000\,\Omega$ in a warm room. The LDR's resistance is $2000\,\Omega$ in dim light and $500\,\Omega$ in bright light. Under which conditions is the p.d. across the LDR equal to $2.0\,\text{V}$?

Oct/Nov 2020

A potential divider is connected to a power supply of voltage $12\ \text{V}$. The resistors $X$ and $Y$ begin with the same resistance. The resistance of $X$ is reduced to half. What change occurs in the output voltage?

Oct/Nov 2020

A student is comparing the resistances of lamps X and Y. He assembles the circuit shown in Fig. 2.1. • He measures the current $I$ in the circuit. • He measures the potential difference (p.d.) $V$ across lamp X. • He swaps lamp X for lamp Y and repeats the current and voltage measurements. • He connects lamp X back into the circuit so that it is in parallel with lamp Y. • He measures the total current $I$ in the circuit. • He measures the p.d. $V$ across lamps X and Y in parallel. The student’s readings are given in Table 2.1.

Oct/Nov 2020

A student arranges two components with resistances that can vary, together with a fixed resistor, across a $6.0\ \text{V}$ supply. In which set of conditions is the voltage across the fixed resistor the highest?

Oct/Nov 2021

A filament lamp is joined to a $240\,\text{V}$ alternating current (a.c.) mains supply.

Oct/Nov 2021

A student sets up a circuit using three identical lamps $P$, $Q$ and $R$, together with a cell and a switch. Lamp $P$ is arranged in series with lamp $R$, the switch and the cell. Lamp $Q$ is connected in parallel with both lamps $P$ and $R$.

Oct/Nov 2021

An electric circuit has two cells and two lamps. The cells are new and fully charged. In which arrangement of the cells and lamps do the cells discharge fastest?

Oct/Nov 2022

A lamp is joined in series to a battery and a variable resistor. The resistance of the variable resistor is slowly reduced. Which statement is correct?

Oct/Nov 2022

In the circuits shown, every cell is the same and each lamp is also the same. The switches are closed. In which circuit are both lamps at their brightest?

Oct/Nov 2022

Circuits P and Q each include two identical resistors, with each resistor having resistance $R$. What is the total resistance of circuit P, and what is the total resistance of circuit Q?

Oct/Nov 2023

A pair of identical resistors is arranged first in series and then in parallel. The resistors in series are attached to a power supply, producing a current of $I_s$. The parallel arrangement is then attached to the same power supply, and the supplied current is $I_p$. Find the ratio $\frac{I_s}{I_p}$?

Oct/Nov 2023

Fig. 6.1 presents a circuit with two identical cells, each having e.m.f. $1.5\,\text{V}$, joined in parallel. It also has two ammeters, a thermistor T and two resistors R and S. Ammeter 1 gives a reading of $0.20\,\text{A}$.

Oct/Nov 2023

Two resistors are arranged in series with a battery, as illustrated. The meter readings for three voltmeters $V_0$, $V_1$ and $V_2$, together with the currents $I_0$, $I_1$ and $I_2$, are also shown. Which row gives the values of the current $I_0$ and the potential difference $V_0$?

Oct/Nov 2024

A cell of e.m.f. $E$ is connected in series with four resistors, each having resistance $R$. From left to right, what current flows through each resistor?

Oct/Nov 2024

A student is studying series and parallel resistor arrangements. The student is given two resistors, X and Y, joined in the circuit illustrated in Fig. 2.1. The resistors are different from each other. The electromotive force (e.m.f.) of the power supply is $3.0\,\text{V}$.

Oct/Nov 2024