In a simple circuit with only an 8-ohm resistor connected to a 24-volt source, what is the voltage across the resistor?

In a simple circuit with only an 8-ohm resistor connected to a 24-volt source, what is the voltage across the resistor?

• A. 8 volts
• B. 0 volts
• C. 24 volts
• D. 12 volts

Answer: (C)

When you have a single resistor connected directly to a voltage source, the resistor must drop the entire source voltage. An ideal 24-volt source sets the voltage across the loop to 24 V, and with only one element there, the full 24 V appears across that resistor. Checking with Ohm’s law: the current would be 24 V / 8 Ω = 3 A, and the voltage across the resistor is 3 A × 8 Ω = 24 V. So the voltage across the resistor is 24 volts. The other values would require additional components to share the drop or a different source.

When you have a single resistor connected directly to a voltage source, the resistor must drop the entire source voltage. An ideal 24-volt source sets the voltage across the loop to 24 V, and with only one element there, the full 24 V appears across that resistor. Checking with Ohm’s law: the current would be 24 V / 8 Ω = 3 A, and the voltage across the resistor is 3 A × 8 Ω = 24 V. So the voltage across the resistor is 24 volts. The other values would require additional components to share the drop or a different source.