A DC motor requires a current of 10 Amperes to operate at full speed. The battery attached supplies 12 Volts. What resistance is required in the circuit to provide exactly 10 A to the motor?

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Multiple Choice

A DC motor requires a current of 10 Amperes to operate at full speed. The battery attached supplies 12 Volts. What resistance is required in the circuit to provide exactly 10 A to the motor?

This question tests Ohm’s law, which links voltage, current, and resistance. To drive the motor at 10 A from a 12 V supply, the circuit’s resistance must be R = V / I = 12 V / 10 A = 1.2 ohms. With this resistance, the current will be exactly 10 A. If the resistance were higher, the current would be less than 10 A; if it were lower, the current would be more than 10 A. The other values would yield currents very different from 10 A (for example, 12 ohms gives about 1 A, 120 ohms about 0.1 A, and 0.12 ohms about 100 A). Therefore, 1.2 ohms is the correct choice.

This question tests Ohm’s law, which links voltage, current, and resistance. To drive the motor at 10 A from a 12 V supply, the circuit’s resistance must be R = V / I = 12 V / 10 A = 1.2 ohms. With this resistance, the current will be exactly 10 A. If the resistance were higher, the current would be less than 10 A; if it were lower, the current would be more than 10 A. The other values would yield currents very different from 10 A (for example, 12 ohms gives about 1 A, 120 ohms about 0.1 A, and 0.12 ohms about 100 A). Therefore, 1.2 ohms is the correct choice.

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