Section 6 - Transformers Flashcards
What voltages do transformers change?
Alternating voltages.
What do transformers do?
They change the size of an alternating current.
How are transformers made?
They have two coils, the primary and the secondary, joined with an iron core.
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How do transformers change the size of voltages?
When alternating voltage is applied across the primary coil, the magnetically soft (iron) core magnetises and demagnetises quickly. This induces and alternating voltage in the secondary coil.
Where are there more turns on a step down transformer?
They step the voltage down. They have more turns on the primary coil.
Where are there more turns on a step up transformer?
On the secondary coil.
How can you do less working out with the transformer equation?
By putting the unknown on the top.
How efficient are transformers ?
Almost 100%
So power in = power out
How are transformers used in the transmission of electricity across long distance?
The voltage produced by power stations is too low to be transmitted efficiently. P = IV, so the lower the voltage the higher the current for a given amount of power, and current causes wires to heat up.
A step up transformer is used to boost the voltage before it is transmitted.
Step down transformers are used at the end of the journey to reduce the voltage so it’s more useful and safer to use.
