In a step-up transformer, how does the secondary current compare to the primary current?

• A. Greater than
• B. Equal to
• C. Less than
• D. None of the above

Answer: (C)

In a step-up transformer, the function is to increase the voltage from the primary winding to the secondary winding. This increase in voltage leads to a decrease in current in the secondary winding compared to the primary winding. The relationship between the primary and secondary sides of a transformer is governed by the principle of conservation of energy, which states that the power input into the transformer must equal the power output, minus any losses.

Power is defined as the product of voltage and current (P = IV). In a step-up transformer, when the voltage increases from primary to secondary, the current must decrease to maintain the same power level. Mathematically, this can be expressed as follows:

If the primary voltage is ( V_p ) and the primary current is ( I_p ), and the secondary voltage is ( V_s ) and the secondary current is ( I_s ), then:

[ P_p = P_s ]

[ V_p \times I_p = V_s \times I_s ]

For a step-up transformer, ( V_s > V_p ) therefore, in order for the equation to hold true, ( I_s ) must be less than ( I_p ) (i.e., ( I_s < I_p \