Question

Question-
The output power in a step-up transformer is ___________.
A. Greater than the input power
B. Equal to the input power
C. Maintained even during the power cut
D. Less than the input power

Answer 1

Hint: Primary winding of the step-up transformer is connected to the input supply and due to this the magnetic field generated and this alternating magnetic field is converted into the electrical power in the secondary winding and this output power at secondary winding will give the voltage greater than the input voltage.

Complete answer:
Step-up transformer is used to increase the input voltage while the step-down transformer is used to decrease the input voltage.
As we all know that the power of any electrical circuit is given by the multiplication of the voltage and the current, i.e. $P = VI$
At the secondary winding the power of the step-up-transformer is the same as that of the primary winding.
Reason- In a step-up transformer the output voltage at the secondary winding increases while the output current at the secondary winding decreases. So, there is both increase and decrees, hence there will be no change in the output power of the transformer.
So, the output power of the transformer will be the same as that of the input power of the transformer.

So, the correct answer is “Option B”.

Note:
The power remains the same for a transformer but the voltage and the current changes. To calculate the output voltage of a transformer we will firstly calculate the transformation ratio (by dividing the number of the secondary winding by the number of the primary windings) and then multiplying the transformation ratio by the input voltage. There is a condition when there will be no change in the current and the voltage, that is when the transformation ratio is equal to 1 (i.e. no of turns in primary windings are equal to that of the secondary windings).