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Flashcards in Transformers Deck (5)
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1

What happens if a wire cuts through a magnetic field?

potential difference is induced across the ends of the conductor

if the wire is part of a complete circuit an electric current will flow in the circuit

2

What does an a.c. in the primary coil of a transformer produce?

it produces a changing magnetic field in the iron core, and hence the secondary coil

this induces an alternating potential difference across the ends of the secondary coil

3

What happens in a step-up transformer?

the p.d. across the secondary coil is greater than the p.d. across the primary coil

the opposite happens with a step-down transformer

4

What happens if a transformer is 100% efficient?

the electrical power output would equal the power input

5

What frequency do switch mode transformers operate at and how do they work?

between 50kHz and 200kHz

they are used because some devices need a smaller p.d. than the 230 V from mains electricity

switch mode transformers use complex electronic circuit, that switch the current on and off rapidly

causing the alternating current to be changed to a high frequency, this reduces p.d.