Which of the following quantities is the same for the primary and secondary of a transformer?

CONCEPT:

• A Transformer is used to convert low voltage (or high current) to high voltage (or low current) and high voltage to low voltage.
• It works on the principle of electromagnetic induction.
• The primary coil has Np turns and the other coil, called the secondary coil, has Ns turns.

• In a transformer, the voltage in the secondary is calculated by

\(\Rightarrow \frac{E_{S}}{E_{P}}=\frac{I_{P}}{I_{S}}=\frac{N_{S}}{N_{P}}\)

EXPLANATION:

• In a transformer, the relation between the voltage, current, and the number of turns at the primary and the secondary coil is given as,

\(\Rightarrow \frac{E_{S}}{E_{P}}=\frac{I_{P}}{I_{S}}=\frac{N_{S}}{N_{P}}\)     -----(1)

• Since the number of turns at the primary and the secondary coil is kept different in the transformer, so by equation 1 it is clear that the voltage and the current will be different at the primary and the secondary coil.
• In an ideal transformer, the power loss is zero.
• So the power at the primary and the secondary coil is the same for the ideal transformer but in actual condition, some power gets converted into heat, and due to various losses, the power at the secondary coil will be less than the primary coil.
• The transformer works on the principle of mutual inductance, so the emf induced at the secondary will be of the same frequency as the primary coil.
• Hence, option 3 is correct.