In a series circuit with 2 Ω and 8 Ω resistors across a 20 V source, what is the voltage across the 2 Ω resistor?

In a series circuit with 2 Ω and 8 Ω resistors across a 20 V source, what is the voltage across the 2 Ω resistor?

• A. 16 V
• B. 4 V
• C. 8 V
• D. 12 V

Answer: (B)

Voltage in a series circuit divides with a constant current through all components, and the split depends on each resistor’s value. The total resistance is 2 Ω + 8 Ω = 10 Ω, so the source current is I = 20 V / 10 Ω = 2 A. The same current flows through the 2 Ω resistor, so its voltage is V = I × R = 2 A × 2 Ω = 4 V. The remaining voltage drops across the 8 Ω resistor (2 A × 8 Ω = 16 V), and 4 V + 16 V = 20 V total. So the voltage across the 2 Ω resistor is 4 V.

Voltage in a series circuit divides with a constant current through all components, and the split depends on each resistor’s value. The total resistance is 2 Ω + 8 Ω = 10 Ω, so the source current is I = 20 V / 10 Ω = 2 A. The same current flows through the 2 Ω resistor, so its voltage is V = I × R = 2 A × 2 Ω = 4 V. The remaining voltage drops across the 8 Ω resistor (2 A × 8 Ω = 16 V), and 4 V + 16 V = 20 V total. So the voltage across the 2 Ω resistor is 4 V.