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Electric current is the rate of flow of electrical charge through a conductor, measured in amperes (A). Free GCSE Physics notes and 14 FAQs.
Electric Charge and Current is part of Current, potential difference and resistance in GCSE AQA Higher Physics.
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Electric current is the rate of flow of electrical charge through a conductor, measured in amperes (A). Free GCSE Physics notes and 14 FAQs.
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Use this lesson to stay inside Current, potential difference and resistance while connecting the detail back to the wider Electricity topic.
Read the core explanations from Electric Charge and Current before testing yourself from memory.
Picture water flowing through pipes in your house. Water only flows when there's pressure pushing it - turn off the pump and the flow stops. Electricity works exactly the same way, but instead of water pressure, we need something called potential difference to push electric charge around a circuit.
Here's the crucial point: for electrical charge to flow through a closed circuit, the circuit must include a source of potential difference. This could be a battery, power supply, or generator. Without it, you get no current flow - just like pipes with no water pressure.
Think of electric current like traffic on a motorway. Current isn't the cars themselves - it's how many cars pass a given point each second. Similarly, electric current is the rate at which electric charge flows past a point in the circuit.
Current is measured in amperes (A), often shortened to 'amps'. A current of 1 amp means 1 coulomb of charge flows past a point every second. In household circuits, currents are typically 1-13 amps. In your phone charger, it's usually around 1-2 amps.
We can calculate exactly how much charge flows using a simple equation. If you know the current and the time, you can work out the total charge that has flowed past any point in the circuit.
This equation tells us that charge flow equals current multiplied by time. Double the current and you get double the charge flow in the same time. Double the time and you get double the charge flow with the same current.
Worked example: Calculating Charge Flow
A current of 2.5 A flows through a wire for 4 minutes. Calculate the charge that flows through the wire. [3 marks]
Answer: 600 C
Notice how we converted minutes to seconds first. The equation only works when time is in seconds, current in amps, and charge in coulombs. This unit conversion catches many students out in exams.
Here's a fundamental rule that trips up many students: in a series circuit, current has the same value at any point. Whether you measure before the first component, between components, or after the last component, you'll get exactly the same reading.
Think of it like a single-lane road. If 100 cars per minute enter the road, then 100 cars per minute must pass every point along the road, and 100 cars per minute must exit. Cars can't disappear or multiply - they just keep moving through.
This happens because charge is conserved. Electrons flowing into a component must equal electrons flowing out. They can't pile up inside components or vanish into thin air. The components convert electrical energy into other forms (light, heat, sound), but the current stays constant.
Examiners love to test your understanding of current with tricky scenarios. Here's how to avoid the most common mistakes and pick up full marks.
For 6-mark questions about current and circuits, structure your answer like this: define current as rate of flow of charge, explain what makes it flow (potential difference), describe what happens in series circuits (same everywhere), then give a specific example with numbers.
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Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
Electric current is the rate of flow of electrical charge through a conductor, measured in amperes (A). A current of 1 amp means 1 coulomb of charge flows past a point every second.
To calculate charge flow, convert time to seconds and use Q = It. A current of 2.5 A flowing for 4 minutes (240 s) gives Q = 2.5 × 240 = 600 C.
For electrical charge to flow through a closed circuit, the circuit must include a source of potential difference, such as a battery, power supply or generator. Potential difference is what 'pushes' current around the circuit; without it there is no current flow.
Current is the same at any point in a series circuit because charge is conserved. Electrons flowing into a component must equal electrons flowing out, so they cannot pile up inside components or vanish, even though the components convert electrical energy into other forms.
A current of 1 amp means 1 coulomb of charge flows past a point every second. Current is measured in amperes (A), often shortened to amps.
Charge flow is calculated with Q = It after converting minutes to seconds. A current of 2.5 A flowing for 4 minutes gives t = 4 × 60 = 240 s, so Q = 2.5 × 240 = 600 C.
Potential difference is what pushes current around a circuit, like water pressure pushing water through pipes. It is the energy difference per unit charge between two points, and without a source of potential difference no current flows.
In Q = It, charge Q is in coulombs (C), current I is in amps (A) and time t is in seconds (s). The equation only works with time in seconds, so minutes must be converted first.
Charge flow doubles if the current doubles over the same time, because Q = It. Doubling the time with the same current also doubles the charge flow.
Currents in household circuits are typically 1–13 amps, and the current in a phone charger is usually around 1–2 amps. Current is the rate of flow of electrical charge, measured in amperes (A).
Charge is conserved in a circuit because electrons flowing into a component must equal electrons flowing out; they cannot pile up inside components or vanish. Components convert electrical energy into other forms such as light, heat and sound, but the current stays constant.
Electric current is like traffic on a motorway: current is not the cars themselves but how many cars pass a given point each second. In the same way, current is the rate at which electric charge flows past a point in the circuit.
Current cannot flow without a source of potential difference, such as a battery, power supply or generator. For electrical charge to flow through a closed circuit, the circuit must include one, just as pipes need water pressure for water to flow.
A full answer about current defines it as the rate of flow of charge, explains that potential difference makes it flow, describes how it is the same everywhere in a series circuit, and gives a specific example with numbers, such as Q = It.