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13.2 Transformers and the National Grid

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Question 21

An illuminated information panel uses a transformer to supply a lamp. The primary coil is connected to a 230 V alternating supply.

QuantityValue
Potential difference across primary coil230 V
Number of turns on primary coil920
Number of turns on secondary coil48

Use the equation

VpVs=NpNs\dfrac{V_{\mathrm{p}}}{V_{\mathrm{s}}}=\dfrac{N_{\mathrm{p}}}{N_{\mathrm{s}}}Vs​Vp​​=Ns​Np​​

a.

Identify whether the transformer is a step-up transformer or a step-down transformer.

[1]
b.

Calculate the potential difference across the secondary coil.

[2]
c.

The current in the secondary coil is 1.5 A.

Calculate the power delivered to the lamp.

Use the equation

P=V×IP=V\times IP=V×I

[2]
d.

The transformer is 100% efficient.

Calculate the current in the primary coil.

Use your answer to part (c) and the equation

I=PVI=\dfrac{P}{V}I=VP​

[2]
Markscheme

13.2 Transformers and the National Grid Questions

  1. GCSE
  2. /Physics
  3. /13.2 Transformers and the National Grid

108 exam-style questions on Edexcel GCSE Physics 13.2 Transformers and the National Grid, covering 13.2.1 Transformers and induction, 13.2.2 The transformer turns-ratio equation, 13.2.3 The National Grid, 13.2.4 The transformer power equation, and 13.2.5 Advantages of high-voltage transmission. Each one has a worked solution and a mark scheme showing where the marks go.

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