What is the name given to a group of cells in an electric circuit?

A group of cells is called a battery .

What is the difference between the circuit symbols for a fixed resistor and a variable resistor ?

The symbol for a variable resistor has an arrow going through it, whereas the symbol for a fixed resistor does not.

What is the function of a relay in a circuit?

A relay uses a small current in one circuit to switch on a much larger current in another circuit.

What is a thermistor ?

A thermistor is a temperature-dependent resistor. This means its resistance changes depending on its temperature.

What is the effect of increased temperature on a thermistor?

When the temperature of a thermistor is increased, its resistance decreases .

What does LDR stand for?

LDR stands for light-dependent resistor .

What is the effect of increased light intensity on an LDR?

When light intensity on an LDR is increased, its resistance decreases . (Remember: L ight D ecreases R esistance - LDR)

True or False? Current is different at different points in a series circuit.

False. Current is the same everywhere in a series circuit.

True or False? In a parallel circuit, the current from the power source is larger than the current in each branch.

True. In a parallel circuit, the current from the power source is larger than the current in each branch.

True or False? The amount of current flowing in a series circuit depends on the potential difference and resistance in the circuit.

True. The amount of current flowing in any circuit depends on the potential difference and resistance in the circuit.

If the e.m.f. of the power source is increased, but everything else in the circuit remains constant, what effect does this have on the current ?

If the e.m.f. (potential difference) of the power source is increased, but everything else in the circuit remains constant, the current will increase .

If the e.m.f. of the power source remains constant, but more components are added to a circuit, what effect does this have on the current ?

Adding components to a circuit increases the total resistance of the circuit, so the current would decrease (for a constant e.m.f.).

True or False? One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.

True. One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.

True or False? One advantage of a series circuit is that if one component stops working the others will still work.

False. An advantage of parallel circuits is that if components in one branch fail, the components in other branches will still work. If one component fails in a series circuit, then the circuit is broken and the current cannot flow.

True or False? Current is conserved at a junction in a parallel circuit. (Extended Tier Only)

True. Current is conserved at a junction in a parallel circuit because charge is always conserved.

True or False? Current always splits equally at a junction in a parallel circuit. (Extended Tier Only)

False. Current will only split equally at a junction if the resistance in each branch is equal.

True or False? When several cells are connected in series, their combined e.m.f. is the product of their individual e.m.f.s.

False. When several cells are connected in series, their combined e.m.f. is the sum of their individual e.m.f.s.

What is the rule for determining the potential difference in a series circuit? (Extended Tier Only)

The total potential difference across the components in a series circuit is equal to the sum of the individual potential differences across each component.

What is the rule for determining the potential difference in a parallel circuit? (Extended Tier Only)

The potential difference across an arrangement of parallel resistances is the same as the potential difference across one branch in the arrangement of the parallel resistances.

What is the rule for calculating the combined resistance of two or more resistors in series?

When two or more resistors are connected in series , the combined resistance is the sum of the individual resistances .

True or False? The combined resistance of two resistors in parallel is less than that of either resistor by itself.

True. The combined resistance of two resistors in parallel is less than that of either resistor by itself.

What is the function of a potential divider? (Extended Tier Only)

A potential divider splits the potential difference of a power source between two components.

True or False? When a potential divider is used in a circuit, the resistor with the largest resistance will have a greater potential difference across it. (Extended Tier Only)

True. When a potential divider is used in a circuit, the resistor with the largest resistance will have a greater potential difference across it.

What is a potentiometer? (Extended Tier Only)

A potentiometer is a type of variable resistor consisting of a coil of wire and sliding contact.

Give one application of a potential divider. (Extended Tier Only)

Examples of applications of potential dividers include: volume controls sensory circuits using LDRs sensory circuits using thermistors

What hazard does damaged insulation on a wire pose?

Exposed wires can cause electric shocks if touched.

What hazard does the overheating of cables pose?

Overheating of cables could lead to melting of the insulation and exposing the wires, or fires .

Why is it dangerous to use electrical circuits in damp conditions?

Moisture can conduct electricity, so using electric circuits in damp conditions could lead to electric shocks , or short circuits which may damage the appliance or even start a fire.

Why is it dangerous to overload plugs, extension leads and multiple sockets when using the mains supply?

If plug sockets are overloaded it can lead to overheating which can cause melting or even fires.

True or False? Mains circuits consist of a live wire, a neutral wire and an earth wire.

True. Mains circuits do consist of a live wire, a neutral wire and an earth wire.

What circuit component must be connected to the live wire in order for the circuit to be turned off safely?

A switch must be connected to the live wire in order for the circuit to be turned off safely.

Why does the casing of an electrical appliance have to be either non-conducting or earthed?

The casing of an electrical appliance must be either non-conducting or earthed to prevent the casing from becoming electrified and causing an electric shock to anyone who touches it.

What is the purpose of a fuse?

A fuse is a safety device designed to break the circuit if the current exceeds a certain amount.

What is the function of a trip switch?

A trip switch is a switch on the consumer unit that will break the circuit if the current exceeds a certain amount.

True or False? A fuse without an earth wire protects the circuit and the cabling for a double-insulated appliance.

True. A fuse without an earth wire protects the circuit and the cabling for a double-insulated appliance.

IGCSEPhysicsCambridge (CIE)Flashcards4. Electricity & MagnetismElectric Circuits & Electrical Safety

Electric Circuits & Electrical Safety (Cambridge (CIE) IGCSE Physics)

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What is the name given to a group of cells in an electric circuit?

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Cards in this collection (37)

What is the name given to a group of cells in an electric circuit?
A group of cells is called a battery.
What is the difference between the circuit symbols for a fixed resistor and a variable resistor?
The symbol for a variable resistor has an arrow going through it, whereas the symbol for a fixed resistor does not.
What is the function of a relay in a circuit?
A relay uses a small current in one circuit to switch on a much larger current in another circuit.
What is a thermistor?
A thermistor is a temperature-dependent resistor.
This means its resistance changes depending on its temperature.
What is the effect of increased temperature on a thermistor?
When the temperature of a thermistor is increased, its resistance decreases.
What does LDR stand for?
LDR stands for light-dependent resistor.
What is the effect of increased light intensity on an LDR?
When light intensity on an LDR is increased, its resistance decreases.
(Remember: Light Decreases Resistance - LDR)
True or False?
Current is different at different points in a series circuit.
False.
Current is the same everywhere in a series circuit.
True or False?
In a parallel circuit, the current from the power source is larger than the current in each branch.
True.
In a parallel circuit, the current from the power source is larger than the current in each branch.
True or False?
The amount of current flowing in a series circuit depends on the potential difference and resistance in the circuit.
True.
The amount of current flowing in any circuit depends on the potential difference and resistance in the circuit.
If the e.m.f. of the power source is increased, but everything else in the circuit remains constant, what effect does this have on the current?
If the e.m.f. (potential difference) of the power source is increased, but everything else in the circuit remains constant, the current will increase.
If the e.m.f. of the power source remains constant, but more components are added to a circuit, what effect does this have on the current?
Adding components to a circuit increases the total resistance of the circuit, so the current would decrease (for a constant e.m.f.).
True or False?
One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.
True.
One advantage of a parallel circuit is that each bulb can be arranged in its own branch with its own switch.
True or False?
One advantage of a series circuit is that if one component stops working the others will still work.
False.
An advantage of parallel circuits is that if components in one branch fail, the components in other branches will still work.
If one component fails in a series circuit, then the circuit is broken and the current cannot flow.
True or False?
Current is conserved at a junction in a parallel circuit. (Extended Tier Only)
True.
Current is conserved at a junction in a parallel circuit because charge is always conserved.
True or False?
Current always splits equally at a junction in a parallel circuit. (Extended Tier Only)
False.
Current will only split equally at a junction if the resistance in each branch is equal.
True or False?
When several cells are connected in series, their combined e.m.f. is the product of their individual e.m.f.s.
False.
When several cells are connected in series, their combined e.m.f. is the sum of their individual e.m.f.s.
What is the rule for determining the potential difference in a series circuit? (Extended Tier Only)
The total potential difference across the components in a series circuit is equal to the sum of the individual potential differences across each component.
What is the rule for determining the potential difference in a parallel circuit? (Extended Tier Only)
The potential difference across an arrangement of parallel resistances is the same as the potential difference across one branch in the arrangement of the parallel resistances.
What is the rule for calculating the combined resistance of two or more resistors in series?
When two or more resistors are connected in series, the combined resistance is the sum of the individual resistances.
True or False?
The combined resistance of two resistors in parallel is less than that of either resistor by itself.
True.
The combined resistance of two resistors in parallel is less than that of either resistor by itself.
State the equation for calculating the combined resistance of two resistors connected in parallel. (Extended Tier Only)
The equation for the combined resistance of two resistors connected in parallel is $\frac{1}{R} = \frac{1}{R_{1}} + \frac{1}{R_{2}}$
Where:
- $R$ = the total combined resistance, measured in ohms (Ω)
- $R_{1}$ = the resistance of the first resistor, measured in ohms (Ω)
- $R_{2}$ = the resistance of the second resistor, measured in ohms (Ω)
What is the function of a potential divider? (Extended Tier Only)
A potential divider splits the potential difference of a power source between two components.
True or False?
When a potential divider is used in a circuit, the resistor with the largest resistance will have a greater potential difference across it. (Extended Tier Only)
True.
When a potential divider is used in a circuit, the resistor with the largest resistance will have a greater potential difference across it.
What is a potentiometer? (Extended Tier Only)
A potentiometer is a type of variable resistor consisting of a coil of wire and sliding contact.
Give one application of a potential divider. (Extended Tier Only)
Examples of applications of potential dividers include:
- volume controls
- sensory circuits using LDRs
- sensory circuits using thermistors
State the potential divider equation.
The potential divider equation is $\frac{R_{1}}{R_{2}} = \frac{V_{1}}{V_{2}}$ Where:
- $R_{1}$ = resistance of the first resistor, measured in ohms ( $Ω$ )
- $R_{2}$ = resistance of the second resistor, measured in ohms ( $Ω$ )
- $V_{1}$ = potential difference across the first resistor, measured in volts (V)
- $V_{2}$ = potential difference across the second resistor, measured in volts (V)
What hazard does damaged insulation on a wire pose?
Exposed wires can cause electric shocks if touched.
What hazard does the overheating of cables pose?
Overheating of cables could lead to melting of the insulation and exposing the wires, or fires.
Why is it dangerous to use electrical circuits in damp conditions?
Moisture can conduct electricity, so using electric circuits in damp conditions could lead to electric shocks, or short circuits which may damage the appliance or even start a fire.
Why is it dangerous to overload plugs, extension leads and multiple sockets when using the mains supply?
If plug sockets are overloaded it can lead to overheating which can cause melting or even fires.
True or False?
Mains circuits consist of a live wire, a neutral wire and an earth wire.
True.
Mains circuits do consist of a live wire, a neutral wire and an earth wire.
What circuit component must be connected to the live wire in order for the circuit to be turned off safely?
A switch must be connected to the live wire in order for the circuit to be turned off safely.
Why does the casing of an electrical appliance have to be either non-conducting or earthed?
The casing of an electrical appliance must be either non-conducting or earthed to prevent the casing from becoming electrified and causing an electric shock to anyone who touches it.
What is the purpose of a fuse?
A fuse is a safety device designed to break the circuit if the current exceeds a certain amount.
What is the function of a trip switch?
A trip switch is a switch on the consumer unit that will break the circuit if the current exceeds a certain amount.
True or False?
A fuse without an earth wire protects the circuit and the cabling for a double-insulated appliance.
True.
A fuse without an earth wire protects the circuit and the cabling for a double-insulated appliance.