Question Constellation Sign up for free AQA · GCSE · Combined Science · Higher
Direct and alternating potential difference
Mains electricity is an ac supply.
Explain the difference between direct and alternating potential difference.
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Marking points
- 1 State that direct potential difference is always in the same direction.
- 2 State that alternating potential difference changes direction.
Full-mark answer
Direct potential difference is always in the same direction, whereas alternating potential difference changes direction.
Why this answer loses marks
AC is bigger than DC.
The credited difference is about direction, not size.