Maintenance Technician Practice Test

Which statement is true regarding a transformer, assuming no power losses?

1. Vp

2. Ip>Is

3. Vp>Vs

4. Ip=Is

The correct answer is: Vp>Vs

In a transformer, the relationship between the primary and secondary voltages is defined by the turns ratio. When there are no power losses in the transformer, the voltage on the primary side (Vp) will always be greater than the voltage on the secondary side (Vs) in the case of a step-down transformer, which reduces voltage. Therefore, the statement that the voltage on the primary side is greater than the voltage on the secondary side is justified. The power for an ideal transformer is given by the equation Pp = Ps, where Pp is the power on the primary side and Ps is the power on the secondary side. Since power is a product of voltage and current (P = VI), the relationship between voltages and currents must also maintain this power equality. In the case of an ideal transformer with the above condition, the voltages and currents can be expressed as Vp * Ip = Vs * Is. Since Vp > Vs, the corresponding current relationship would reflect that Ip is less than Is for power to remain constant, which is inversely proportional. This context confirms that the proper relationship stands as Vp > Vs. Considering this, the selected statement accurately reflects the underlying principles governing ideal transformer operation in the absence of power losses.