The voltage across the transformer primary during operation is:

The voltage across the transformer primary during operation is:

• A. 120 V
• B. 240 V
• C. 12 V
• D. 480 V

Answer: (B)

The voltage on the primary winding is the voltage of the supply feeding the transformer. In this setup, the transformer is connected to a 240-volt line, so during operation the primary sees and uses that 240 V. The secondary voltage is set by the turns ratio, not by the input; a 240 V primary could step down to 120 V on the secondary, for example. The other numbers correspond to voltages that would be on the secondary or to different primary voltages, but they aren’t the source voltage feeding this transformer.

The voltage on the primary winding is the voltage of the supply feeding the transformer. In this setup, the transformer is connected to a 240-volt line, so during operation the primary sees and uses that 240 V. The secondary voltage is set by the turns ratio, not by the input; a 240 V primary could step down to 120 V on the secondary, for example. The other numbers correspond to voltages that would be on the secondary or to different primary voltages, but they aren’t the source voltage feeding this transformer.