Extra TopicsWorked Example

Worked Examples

Part of National Grid & Transformers · GCSE GCSE Physics revision

This worked example covers Worked Examples 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 5 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 5 of 12

Practice

14 questions

Recall

12 flashcards

🧮 Worked Examples

Example 1 — Finding Output Voltage

Question: A step-up transformer has 500 turns on the primary coil and 10,000 turns on the secondary. The primary voltage is 25,000 V. Calculate the secondary voltage.

Using: V_p / V_s = N_p / N_s

25,000 / V_s = 500 / 10,000

25,000 / V_s = 0.05

V_s = 25,000 / 0.05 = 500,000 V

Example 2 — Finding Output Current

Question: A transformer steps up voltage from 230 V to 23,000 V. The primary current is 10 A. Assuming 100% efficiency, find the secondary current.

Using: V_p × I_p = V_s × I_s

230 × 10 = 23,000 × I_s

2,300 = 23,000 × I_s

I_s = 2,300 / 23,000 = 0.1 A

Voltage increased by ×100, so current decreased by ×100 (from 10 A to 0.1 A).

Keep building this topic

Read this section alongside the surrounding pages in National Grid & Transformers. That gives you the full topic sequence instead of a single isolated revision point.

The Transformer Equations Key Terms The Cleverest Solution in Engineering History How the National Grid Works

Practice Questions for National Grid & Transformers

What is the function of a step-up transformer in the National Grid?

A. To increase current and decrease voltage for transmission
B. To increase voltage and decrease current for transmission
C. To convert AC to DC for transmission
D. To store electrical energy during low-demand periods

1 markfoundation

Explain why electricity is transmitted at high voltage and low current through the National Grid power cables.

3 marksstandard

Quick Recall Flashcards

How does a transformer work?

AC in primary creates changing magnetic field → iron core transfers field to secondary → changing field induces voltage in secondary (electromagnetic induction)

What voltage do homes receive?

230 V

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The Transformer Equations

Key Terms