Exam Focus — National Grid and Transformers
Part of National Grid & Transformers — GCSE Physics
This exam focus covers Exam Focus — National Grid and Transformers within National Grid & Transformers for GCSE Physics. Revise National Grid & Transformers in Extra Topics for GCSE Physics with 13 exam-style questions and 12 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 10 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 10 of 12
Practice
13 questions
Recall
12 flashcards
🎯 Exam Focus — National Grid and Transformers
Most Common Question Types
- Explain why the National Grid transmits at high voltage [3-4 marks] — must reference P = I²R and link high V to low I to low power loss
- Calculate secondary voltage or turns using the turns ratio equation [2-3 marks]
- Calculate secondary current using the power equation [2-3 marks]
- Explain how a transformer works [4 marks] — describe AC → changing magnetic field → iron core → induction in secondary
- Identify step-up vs step-down from turns or voltage values [1-2 marks]
What Examiners Want to See
For "explain why high voltage" questions, a full-mark answer must: (1) state that high voltage means low current, (2) reference P = I²R, (3) state that lower current means less power wasted as heat in the cables. Many students lose marks by only stating "less energy lost" without explaining why via the equation.