If the load on the secondary of a small 10 to 1 step-up transformer is 100 watts, what is the power being drawn from the power line by the primary?

In a transformer, power transfer ideally follows the principle of conservation of energy, meaning that the power output on the secondary side cannot exceed the power input on the primary side. However, because there are real-world inefficiencies in transformers—such as losses due to resistance in the copper windings, core losses due to hysteresis and eddy currents, and other factors—the power drawn from the primary side will always be greater than the power on the secondary side when the load is present.

In this scenario, a small step-up transformer is described with a step-up ratio of 10 to 1, indicating that the voltage at the secondary side is increased by a factor of 10 compared to the primary voltage. If the load on the secondary is 100 watts, the power drawn from the primary must account for these inefficiencies. Therefore, the primary side will draw more power than what is output on the secondary side (100 watts) to compensate for losses.

Given that these losses typically ensure that the output power is less than the input power under load conditions, the correct conclusion will be that the power drawn from the primary will indeed be more than 100 watts to sustain the output while overcoming all existing inefficiencies.