Apply Ohm's Law to a DC circuit with a 12 V source and a 4 Ω load. What is the current and the power?

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Multiple Choice

Apply Ohm's Law to a DC circuit with a 12 V source and a 4 Ω load. What is the current and the power?

Explanation:
The current, resistance, and voltage in a DC circuit follow Ohm’s Law: V = IR, and power is P = VI (also P = I^2R or P = V^2/R). With a 12 V source and a 4 Ω load, the current is I = V/R = 12/4 = 3 A. The power drawn is P = VI = 12 × 3 = 36 W (which is also I^2R = 3^2 × 4 = 36 W). This pair is the only one consistent with both the given voltage and load. If the current were 4 A, the required voltage would be V = IR = 4 × 4 = 16 V, which conflicts with the 12 V source. If the current were 6 A, V would be 24 V. If the current were 2 A, the implied load would be R = V/I = 12/2 = 6 Ω, not 4 Ω.

The current, resistance, and voltage in a DC circuit follow Ohm’s Law: V = IR, and power is P = VI (also P = I^2R or P = V^2/R). With a 12 V source and a 4 Ω load, the current is I = V/R = 12/4 = 3 A. The power drawn is P = VI = 12 × 3 = 36 W (which is also I^2R = 3^2 × 4 = 36 W). This pair is the only one consistent with both the given voltage and load.

If the current were 4 A, the required voltage would be V = IR = 4 × 4 = 16 V, which conflicts with the 12 V source. If the current were 6 A, V would be 24 V. If the current were 2 A, the implied load would be R = V/I = 12/2 = 6 Ω, not 4 Ω.

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