The Turns Ratio Rule — "UP means MORE"
Step-UP transformer = MORE turns on secondary side. Fewer → More = voltage goes Up. The pattern: Up = More turns secondary, More voltage out.
Remembering the Equations
The voltage/turns equation: think of it as two fractions that must be equal:
Vp / Vs = Np / Ns → "Primary over Secondary = Primary over Secondary"
The power equation: think of both sides of the transformer having the same "power budget":
Vp × Ip = Vs × Is → "Power in = Power out"
Why High Voltage for Transmission — the I² reminder
P(loss) = I²R. The current is squared, so halving current quarters the loss. High voltage means low current. Low current means tiny losses. Remember: high V → low I → tiny I² loss.
This memory aid covers Memory Aids within National Grid & Transformers for GCSE Physics. Revise National Grid & Transformers in Extra Topics for GCSE Physics with 14 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 9 of 12 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
Practice questions for National Grid & Transformers
What is the function of a step-up transformer in the National Grid?
Explain why electricity is transmitted at high voltage and low current through the National Grid power cables.