What happens to current when voltage is increased in a step-up transformer?

In a step-up transformer, the primary function is to increase voltage from the primary winding to the secondary winding. This increase in voltage leads to a corresponding decrease in current. The principle governing this behavior is based on the conservation of power. In an ideal transformer, the power input to the primary winding is equal to the power output from the secondary winding, minus any losses.

Power is defined as the product of voltage and current, which can be expressed as ( P = V \times I ). When the voltage is stepped up, the current must adjust to maintain the same power level. Therefore, if the voltage increases, the current must subsequently decrease to keep the overall power constant (as long as we ignore losses).

This relationship can be mathematically described using the formula for transformers:

[

\frac{V_p}{V_s} = \frac{N_p}{N_s} \quad \text{and} \quad \frac{I_s}{I_p} = \frac{N_p}{N_s}

]

where ( V_p ) and ( V_s ) are the primary and secondary voltages, ( I_p ) and ( I_s ) are the primary and secondary currents, and (