Find the voltage across the 8-ohm resistor.

• A. 8 volts.
• B. 16 volts.
• C. 20.4 volts.
• D. 24 volts.

Answer: (D)

Start with the main idea: the voltage across a resistor comes from Ohm’s law, V = I × R. To know the voltage across the 8‑ohm resistor, you need the current through that resistor (or the voltage already known across it).

If the resistor carries 3 A, then V = 3 A × 8 Ω = 24 V. So a voltage of 24 volts across the resistor means the path feeding it delivers 3 A through that 8‑ohm element (whether it’s across a 24 V supply or across a node with a 24 V difference in the circuit).

The other values would imply different currents: 8 volts would mean 1 A, 16 volts would mean 2 A, and 20.4 volts would mean 2.55 A. Unless the circuit forces those currents through this resistor, those voltages wouldn’t be correct.

Therefore, the voltage across the 8‑ohm resistor is 24 volts.