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Electricity and Magnetism
Quick questions on Alternating current and transformers: H2 Physics Electricity and Magnetism
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is power in an a.c. circuit?Show answer
The mean power dissipated in a resistor uses r.m.s. values:
What is the ideal transformer?Show answer
A transformer has a primary coil of turns and a secondary of turns wound on a common iron core. An alternating current in the primary produces a changing flux in the core, which links the secondary and induces an e.m.f. there (Faraday's law). For an ideal transformer:
What is power conservation in an ideal transformer?Show answer
An ideal transformer is 100 percent efficient, so the power out equals the power in:
What is q1?Show answer
State the relationship between the peak and r.m.s. values of a sinusoidal voltage. [1 mark]
What is q2?Show answer
A transformer steps down to . If the primary has turns, find the number of secondary turns. [2 marks]
What is q3?Show answer
Explain why electrical power is transmitted at high voltage. [3 marks]
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