A transformer has an input voltage to the primary of 120 Th

A transformer has an input voltage to the primary of 120 , The primary has 500 turns of wire and the secondary has 200 turns of wire. A 50ohm resistor is connected across the secondary winding, what is the power dissipated in the resistor?

Solution

For a transformer, we know that the ratio of the voltage across the primary and secondary winding is same as the ratio of the number of turns in them.

Primary Voltage/ Secondary Voltage = Number of turns in primary / Number of turns in secondary

That is, 120 / V = 500 / 200

or, V = 120 x 200 / 500 = 48 Volts

That is the voltage across the secondary winding is 48 Volts. Now, we know that there is resistor of 50 Ohms connected across the secondary winding.

And the power dissipated in a circuit with voltage V and resistance R is given as: P = V²/R

or, P = 48² / 50 = 46.08 Watts

Therefore the required power dissipation is 46.08 Watts