A transformer with a 120-volt primary voltage supplies 250 watts to a transmitter. Neglecting losses, what is the approximate primary current?

To find the current in the primary winding, you must use the basic electrical power equation: Power (P) = Voltage (E) × Current (I). By rearranging this formula to solve for current, you get I = P / E. When you plug in the values provided in the question, you calculate 250 watts / 120 volts, which equals 2.0833 amperes. Rounding this calculation to the nearest tenth gives approximately 2.1 amperes. Distractors often result from performing the math backwards, such as dividing the voltage by the power (120 / 250 = 0.48 A).