๐ฏ Common Question Types:
- Calculate power from V and I (2 marks)
- Calculate energy in joules from P and t in seconds (2 marks)
- Calculate energy in kWh and cost (3 marks)
- Choose and apply correct power equation (2โ3 marks)
- Explain why National Grid uses high voltage (3 marks โ Higher)
๐ Key Command Words:
- Calculate โ show equation, substitution, and units
- Explain โ state the equation and say what happens to each variable
- Compare โ state which uses more energy and why
- Evaluate โ consider pros and cons of a claim
โ ๏ธ Common Mistakes to Avoid:
- Using kW ร seconds instead of kW ร hours for kWh
- Forgetting to divide watts by 1000 to get kilowatts
- Using the wrong power equation (check what quantities you're given)
- Forgetting to state units: W, J, kWh
- Confusing energy (J or kWh) with power (W or kW)
Quick Check: A component has a resistance of 10 ฮฉ and carries 3 A of current. Calculate the power dissipated.
Use P = IยฒR = 3ยฒ ร 10 = 9 ร 10 = 90 W.
This exam tips covers Exam Tips for Electrical Power and Energy within Electrical Power & Energy for GCSE Physics. Revise Electrical Power & Energy in Electricity for GCSE Physics with 15 exam-style questions and 30 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 14 of 15 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Practice questions for Electrical Power & Energy
What is the unit of electrical power?
A television has a power rating of 120 W and is left on for 3 hours. Calculate the energy transferred by the television in this time. Use the equation: energy transferred = power x time. Give your answer in joules.