How is mains electricity produced?
You should know how a transformer works and how to calculate the voltages [voltage: The potential difference of a cell, electrical supply or electric component. It is measured in volts, 'V'. ] involved.
A transformer needs an alternating currentalternating current: Also called 'AC'. This is an electric current that regularly changes its direction and size. that will create a changing magnetic field. A changing magnetic field also induces a changing voltage in a coil. This is the basis of how a transformer works:
It's important to know that:
The ratio between the voltages in the coils is the same as the ratio of the number of turns in the coils.
primary voltage / secondary voltage = turns on primary / turns on secondary
This can also be written as:
Vp/Vs = Np/Ns
Step-up transformers have more turns on the secondary coil than they do on the primary coil.
Step-down transformers have fewer turns on the secondary coil than they do on the primary coil.
Check your understanding of this by having a go at the activity.
Now try a Test Bite - Higher
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