If I = 4 A and R = 6 ohms, what is E?

• A. 6 V
• B. 24 V
• C. 12 V
• D. 96 V

Answer: (B)

Voltage follows Ohm’s law: E = I × R. With a current of 4 A through a resistance of 6 Ω, the voltage is E = 4 × 6 = 24 V. The other numbers would require different resistances given the same current (for example, 6 V would need 1.5 Ω, 12 V would need 3 Ω, and 96 V would need 24 Ω). Since the resistance is 6 Ω, the voltage comes out to 24 volts.