AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
For electrical charge to flow through a closed circuit the circuit must…
Full specification wording
Electrical charge and current: For electrical charge to flow through a closed circuit the circuit must include a source of potential difference.
Charge does not flow on its own; something has to push it.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 1 of 2
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Charge does not flow on its own; something has to push it. That push is a potential difference, supplied by a cell, a battery or a mains supply. A cell or battery transfers energy from its chemical store to the charges and drives them round the circuit. Two conditions must both hold for charge to flow. There must be a source of potential difference, and the circuit must be complete, forming a closed loop of conductors with no gaps. Open a switch, blow a fuse or break a wire in a series circuit and the current everywhere stops instantly. However, in a parallel circuit, a break in one branch does not stop current flowing in other intact branches. Adding more cells in series raises the potential difference, so the current increases; closing a switch that adds a parallel branch lowers the total resistance, so the current from the supply increases.
What earns the marks
- Stating that a source of potential difference is needed to make charge flow.
- Stating that the circuit must be closed or complete.
- Explaining that an open switch or break stops the current throughout a series circuit.
- Linking a change in supply potential difference or total resistance to a change in current.
Common mistakes and how to put them right
Saying the battery supplies the charges, when the charges are already in the wires and the battery supplies the potential difference.
Claiming current is used up as it goes round the circuit.
Thinking a break in a series circuit only stops the current after the break, rather than everywhere instantly.
Assuming a break in one branch of a parallel circuit stops the current in all other branches.
Exam tips
- Name both conditions, the source and the complete circuit, because a one-condition answer only scores half.
- Use the phrase charge flows rather than electricity flows, which is too vague to credit.
- When a switch is closed or opened, check if it is in a series loop or a parallel branch before deciding if the whole current stops.
Try the lesson
The start of the Electrical charge and current: For electrical charge to flow through a closed circuit the circuit must include a source of potential difference. lesson, made from checked teaching notes for this specification point.
Have a go first
A student connects a lamp and a closed switch together with connecting wires. They notice that the lamp does not light up because no electrical charge is flowing. What must be added to the circuit for electrical charge to flow?
Listen
Charge does not flow on its own; something has to push it. That push is a potential difference, supplied by a cell, a battery or a mains supply. A cell or battery transfers energy from its chemical store to the charges and drives them round the circuit. Two conditions must both hold for charge to flow. There must be a source of potential difference, and the circuit must be complete, forming a closed loop of conductors with no gaps. Open a switch, blow a fuse or break a wire in a series circuit and the current everywhere stops instantly. However, in a parallel circuit, a break in one branch does not stop current flowing in other intact branches. Adding more cells in series raises the potential difference, so the current increases; closing a switch that adds a parallel branch lowers the total resistance, so the current from the supply increases. A strong answer earns marks for these points. stating that a source of potential difference is needed to make charge flow. stating that the circuit must be closed or complete. explaining that an open switch or break stops the current throughout a series circuit. linking a change in supply potential difference or total resistance to a change in current. Exam tip: Name both conditions, the source and the complete circuit, because a one-condition answer only scores half.
Key words
Say what each word means before you turn the card.
potential difference
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closed circuit
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series circuit
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parallel circuit
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See every definition
- potential difference
- The push supplied by a cell, a battery or a mains supply that makes electrical charge flow through a closed circuit.
- closed circuit
- A complete loop of conductors with no gaps, which the circuit must form for electrical charge to flow.
- series circuit
- A circuit in which opening a switch, blowing a fuse or breaking a wire stops the current everywhere instantly.
- parallel circuit
- A circuit in which a break in one branch does not stop current flowing in other intact branches.
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