This worked example covers Worked Examples within Power for GCSE Physics. Revise Power in Energy for GCSE Physics with 14 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 7 of 12 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 7 of 12
Practice
14 questions
Recall
25 flashcards
🧮 Worked Examples
Example 1 — Basic power calculation:
A person does 2,400 J of work climbing stairs in 40 seconds. Calculate their power output.
- Write the formula: P = W/t
- Substitute values: P = 2,400 / 40
- Calculate: P = 60 W
Example 2 — Rearranging to find time:
A 1,500 W hairdryer transfers 90,000 J. How long was it switched on?
- Rearrange: t = E/P
- Substitute: t = 90,000 / 1,500
- Calculate: t = 60 s
Example 3 — Electrical power:
A lamp has a current of 0.5 A and operates at 12 V. Calculate its power.
- Formula: P = IV
- Substitute: P = 0.5 × 12
- Calculate: P = 6 W
Example 4 — Energy cost (kWh):
A 2 kW electric heater is used for 3 hours. Electricity costs 30p per kWh. Find the cost.
- Energy = P × t = 2 × 3 = 6 kWh
- Cost = 6 × 30p = 180p = £1.80
Quick Check: A 50 W electric motor runs for 2 minutes. How much energy does it transfer?
E = P × t = 50 × 120 = 6,000 J. Remember to convert minutes to seconds: 2 min = 120 s.
Keep building this topic
Read this section alongside the surrounding pages in Power. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Power
Which of the following is the correct definition of power?
State what is meant by the term 'power' in physics and state its unit.
Quick Recall Flashcards
14 questions on Power — practise free
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