Define a series circuit .

A series circuit is a circuit that has only one loop, so there is only one path that electrons can take.

Define a parallel circuit .

A parallel circuit is a circuit that has two or more loops, giving electrons more than one path to take. It contains junctions and branches .

What is true of the current at every point in a series circuit?

The current is the same at every point in a series circuit, since all components share the same single path.

How does the total current flowing into a junction compare to the total current flowing out of it?

They are equal — current is always conserved at a junction because charge cannot be created or destroyed.

Increasing the number of components in a series circuit ______ the total resistance, which ______ the current.

Increasing the number of components in a series circuit increases the total resistance, which decreases the current.

True or False? In a parallel circuit, the current always splits equally between all branches.

False. Current only splits equally if the resistance in each branch is identical; otherwise more current flows through the branch with lower resistance.

In a circuit, ammeter A 0 reads 10 A where the current enters a junction, and ammeter A 1 reads 6 A on one branch. What does ammeter A 2 read on the other branch?

4 A , since the branch currents must add up to the total current entering the junction: 10 A − 6 A = 4 A.

Define a parallel circuit .

A parallel circuit consists of two or more components attached across different branches of the circuit.

In a series circuit, two non-identical resistors are connected together. Which one has the higher voltage across it?

The resistor with the higher resistance has the higher voltage across it; the one with lower resistance has the lower voltage.

How does the voltage across each branch of a parallel circuit compare to the voltage of the power supply?

The voltage across each branch is the same as the voltage of the power supply.

Give one advantage of connecting components in series.

All of the components can be controlled by a single switch , and fewer wires are required than in a parallel circuit.

Give one disadvantage of connecting components in series.

The components cannot be controlled separately , and if one component breaks, all the other components stop working.

Give one advantage of connecting components in parallel.

Each component can be individually controlled using its own switch, and if one component breaks, the others continue to function.

In a series circuit, the total voltage of the power supply is ______ between the components.

In a series circuit, the total voltage of the power supply is shared between the components.

True or False? For two identical components connected in series, the voltage across each one is equal to half the total supply voltage.

True. Since the components are identical (equal resistance), they share the total voltage equally, each taking half .

What happens to the total resistance of a series circuit as more resistors are added?

The total resistance increases , since the charge now has more resistors to pass through.

In a series circuit, how does the total voltage of the power supply relate to the voltages across the individual resistors?

The total voltage is equal to the sum of the voltages across each of the individual resistors.

For components connected in series, the ______ is the same at all points, while the ______ is shared between the components.

For components connected in series, the current is the same at all points, while the voltage is shared between the components.

True or False? In a parallel circuit, the total resistance is greater than that of any individual component.

False. In a parallel circuit, the total resistance is actually less than that of each individual component; it is series circuits where the total resistance is the sum of the individual resistances.

Resistance is the opposition to the flow of current; the higher the resistance of a circuit, the lower the current.

What does a linear IV graph (a straight line through the origin) show about a component's resistance?

The resistance is constant — current is directly proportional to voltage.

Name components that produce non-linear IV graphs.

Filament lamps, diodes, LDRs and thermistors.

Why does the resistance of a filament lamp increase as the current through it increases?

The higher current raises the filament's temperature , causing the atoms in the metal lattice to vibrate more, making it harder for free electrons to pass through — so resistance increases.

What is meant by a diode being in forward bias ?

Forward bias is when current flows in the direction of the diode's arrowhead symbol. On the IV graph this shows as a sharp increase in current and voltage, indicating the diode's resistance is very low .

What happens when a diode is connected in reverse bias ?

The diode has very high resistance and no current flows; on the IV graph this shows as a zero reading of current across that range of voltages.

When investigating the IV characteristic of a component, current is the ______ variable and voltage is the ______ variable.

When investigating the IV characteristic of a component, current is the independent variable and voltage is the dependent variable.

True or False? A variable resistor changes its resistance by changing the length of wire in the circuit.

True. A longer length of wire has more resistance than a shorter length, and this is how variable resistors change resistance.

Define a thermistor .

A thermistor is a resistor whose resistance depends on its temperature.

Define a light-dependent resistor (LDR) .

A light-dependent resistor (LDR) is a resistor whose resistance depends on the light intensity on it.

How does the resistance of a thermistor change as its temperature increases?

The resistance decreases as temperature increases (and increases as temperature decreases).

How does the resistance of an LDR change as light intensity increases?

The resistance decreases as light intensity increases (and increases as light intensity decreases).

Lamps and ______ illuminate when a current flows through them, making them useful for indicating the presence of a current in a circuit.

Lamps and LEDs illuminate when a current flows through them, making them useful for indicating the presence of a current in a circuit.

True or False? An LED will light up regardless of which way round it is connected in a circuit.

False. An LED is a type of diode, so it only allows current to flow in one direction — connected the wrong way round, it will not light up.

What do thermistors and LDRs have in common, and what is the key difference between them?

Both are resistors whose resistance changes with an environmental condition. A thermistor's resistance depends on temperature , whereas an LDR's resistance depends on light intensity .

IGCSEPhysicsEdexcelPhysics (Modular)Unit 1Flashcards2. ElectricityComponents in Series & Parallel Circuits

Components in Series & Parallel Circuits (Edexcel IGCSE Physics (Modular): Unit 1): Flashcards

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FrontCurrent in Series & Parallel
Define a series circuit.

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Cards in this collection (37)

Define a series circuit.
A series circuit is a circuit that has only one loop, so there is only one path that electrons can take.
Define a parallel circuit.
A parallel circuit is a circuit that has two or more loops, giving electrons more than one path to take. It contains junctions and branches.
What is true of the current at every point in a series circuit?
The current is the same at every point in a series circuit, since all components share the same single path.
How does the total current flowing into a junction compare to the total current flowing out of it?
They are equal — current is always conserved at a junction because charge cannot be created or destroyed.
Increasing the number of components in a series circuit ______ the total resistance, which ______ the current.
Increasing the number of components in a series circuit increases the total resistance, which decreases the current.
True or False?
In a parallel circuit, the current always splits equally between all branches.
False.
Current only splits equally if the resistance in each branch is identical; otherwise more current flows through the branch with lower resistance.
In a circuit, ammeter A₀ reads 10 A where the current enters a junction, and ammeter A₁ reads 6 A on one branch. What does ammeter A₂ read on the other branch?
4 A, since the branch currents must add up to the total current entering the junction: 10 A − 6 A = 4 A.
Define a parallel circuit.
A parallel circuit consists of two or more components attached across different branches of the circuit.
In a series circuit, two non-identical resistors are connected together. Which one has the higher voltage across it?
The resistor with the higher resistance has the higher voltage across it; the one with lower resistance has the lower voltage.
How does the voltage across each branch of a parallel circuit compare to the voltage of the power supply?
The voltage across each branch is the same as the voltage of the power supply.
Give one advantage of connecting components in series.
All of the components can be controlled by a single switch, and fewer wires are required than in a parallel circuit.
Give one disadvantage of connecting components in series.
The components cannot be controlled separately, and if one component breaks, all the other components stop working.
Give one advantage of connecting components in parallel.
Each component can be individually controlled using its own switch, and if one component breaks, the others continue to function.
In a series circuit, the total voltage of the power supply is ______ between the components.
In a series circuit, the total voltage of the power supply is shared between the components.
True or False?
For two identical components connected in series, the voltage across each one is equal to half the total supply voltage.
True.
Since the components are identical (equal resistance), they share the total voltage equally, each taking half.
Define the total resistance of resistors connected in series.
The total resistance of resistors in series is the sum of their individual resistances:
$R = R_{1} + R_{2}$
where R, R₁ and R₂ are resistances in ohms (Ω).
What happens to the total resistance of a series circuit as more resistors are added?
The total resistance increases, since the charge now has more resistors to pass through.
In a series circuit, how does the total voltage of the power supply relate to the voltages across the individual resistors?
The total voltage is equal to the sum of the voltages across each of the individual resistors.
For components connected in series, the ______ is the same at all points, while the ______ is shared between the components.
For components connected in series, the current is the same at all points, while the voltage is shared between the components.
A series circuit has a combined resistance of 60 Ω, made up of three resistors: 30 Ω, an unknown R₂, and 10 Ω. What is R₂?
R₂ = 60 Ω − 30 Ω − 10 Ω = 20 Ω, using $R = R_{1} + R_{2} + R_{3}$ .
True or False?
In a parallel circuit, the total resistance is greater than that of any individual component.
False.
In a parallel circuit, the total resistance is actually less than that of each individual component; it is series circuits where the total resistance is the sum of the individual resistances.
A series circuit has a cell supplying a current of 2 A to a fixed resistor of resistance 4 Ω. What is the current through, and the voltage across, the fixed resistor?
The current through the resistor is 2 A (current is the same at all points in a series circuit). Using $V = I \times R$ , the voltage is V = 2 A × 4 Ω = 8 V.
Define resistance.
Resistance is the opposition to the flow of current; the higher the resistance of a circuit, the lower the current.
What does a linear IV graph (a straight line through the origin) show about a component's resistance?
The resistance is constant — current is directly proportional to voltage.
Name components that produce non-linear IV graphs.
Filament lamps, diodes, LDRs and thermistors.
Why does the resistance of a filament lamp increase as the current through it increases?
The higher current raises the filament's temperature, causing the atoms in the metal lattice to vibrate more, making it harder for free electrons to pass through — so resistance increases.
What is meant by a diode being in forward bias?
Forward bias is when current flows in the direction of the diode's arrowhead symbol. On the IV graph this shows as a sharp increase in current and voltage, indicating the diode's resistance is very low.
What happens when a diode is connected in reverse bias?
The diode has very high resistance and no current flows; on the IV graph this shows as a zero reading of current across that range of voltages.
When investigating the IV characteristic of a component, current is the ______ variable and voltage is the ______ variable.
When investigating the IV characteristic of a component, current is the independent variable and voltage is the dependent variable.
True or False?
A variable resistor changes its resistance by changing the length of wire in the circuit.
True.
A longer length of wire has more resistance than a shorter length, and this is how variable resistors change resistance.
Define a thermistor.
A thermistor is a resistor whose resistance depends on its temperature.
Define a light-dependent resistor (LDR).
A light-dependent resistor (LDR) is a resistor whose resistance depends on the light intensity on it.
How does the resistance of a thermistor change as its temperature increases?
The resistance decreases as temperature increases (and increases as temperature decreases).
How does the resistance of an LDR change as light intensity increases?
The resistance decreases as light intensity increases (and increases as light intensity decreases).
Lamps and ______ illuminate when a current flows through them, making them useful for indicating the presence of a current in a circuit.
Lamps and LEDs illuminate when a current flows through them, making them useful for indicating the presence of a current in a circuit.
True or False?
An LED will light up regardless of which way round it is connected in a circuit.
False.
An LED is a type of diode, so it only allows current to flow in one direction — connected the wrong way round, it will not light up.
What do thermistors and LDRs have in common, and what is the key difference between them?
Both are resistors whose resistance changes with an environmental condition. A thermistor's resistance depends on temperature, whereas an LDR's resistance depends on light intensity.

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