A transformer is used to produce a mains voltage of 230V for a house. There are 2000 turns on the primary coil and 20 turns on the secondary coil. What voltage must the power lines have supplied to this transformer?

2.3 volts

Explanation:

The transformer turns ration is calculated by dividing the number of turns in the primary coil by the number of turns in the secondary coil.

Mathematically;  

This ratio is equal to voltage of primary winding divided by the voltage of the secondary winding. i.e.

This means you can combine the two equations as;

Given that;

Substitute the values in the equation as;

2000/20 =230/Vs

Vs=230/100

Vs=2.3 v

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