A 5-ohm resistor carries a current of 2 A. What is the potential difference across it?

A 5-ohm resistor carries a current of 2 A. What is the potential difference across it?

• A. 2.5 V
• B. 0.4 V
• C. 5 V
• D. 10 V

Answer: (D)

Ohm’s law is at play: the voltage across a resistor equals the current through it times its resistance (V = I × R). Here, 2 A flows through a 5 Ω resistor, so the voltage drop is 2 × 5 = 10 V. So the potential difference is 10 volts. The other values would require different currents or resistances (for example, 2.5 V would need 0.5 A, 0.4 V would need 0.08 A, and 5 V would need 1 A).

Ohm’s law is at play: the voltage across a resistor equals the current through it times its resistance (V = I × R). Here, 2 A flows through a 5 Ω resistor, so the voltage drop is 2 × 5 = 10 V. So the potential difference is 10 volts. The other values would require different currents or resistances (for example, 2.5 V would need 0.5 A, 0.4 V would need 0.08 A, and 5 V would need 1 A).