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GCSE Physics · key term
The energy transferred per unit charge between two points, measured in volts (V).
Used by Edexcel and OCR
Specification 10.33 · Paper 2
Revise: DC vs AC VoltagePotential difference, usually called voltage, is measured between two points. It tells us how much energy is transferred per unit charge. A voltage also has a polarity: one point can be at a higher potential than the other.
Specification P8.2c · Paper 2 (Foundation), Paper 4 (Higher)
The energy transferred per unit of electric charge between two points, measured in volts (V).
Revise: National GridThe route has two different voltage stages. Power leaves the power station area for long-distance transmission at high voltage. Near the places where people use it, the voltage is reduced.
On a voltage–time graph, identify a direct voltage by its unchanged polarity: the trace stays on one side of 0 V. An alternating voltage crosses 0 V and takes both positive and negative values.
Do not say merely that an alternating voltage “changes”. Its defining feature is that its polarity reverses repeatedly; a varying voltage that never reverses polarity is still direct.
When comparing traces, refer explicitly to the axes: time is on the horizontal axis and potential difference is on the vertical axis.
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