In a DC circuit with a fixed resistance, what happens to the current if the voltage doubles?

In a DC circuit with a fixed resistance, what happens to the current if the voltage doubles?

• A. It doubles.
• B. It halves.
• C. It remains the same.
• D. It becomes zero.

Answer: (A)

Current through a fixed resistor follows Ohm’s law: I = V/R. When the resistance is constant, the current changes in direct proportion to the voltage. So if the voltage doubles, the current doubles as well because I becomes (2V)/R, which equals 2 × (V/R). For example, with a 100-ohm resistor, raising the voltage from 10 V to 20 V makes the current go from 0.10 A to 0.20 A. The other options would require changing the resistance or breaking the direct proportionality, which isn’t the case here.

Current through a fixed resistor follows Ohm’s law: I = V/R. When the resistance is constant, the current changes in direct proportion to the voltage. So if the voltage doubles, the current doubles as well because I becomes (2V)/R, which equals 2 × (V/R). For example, with a 100-ohm resistor, raising the voltage from 10 V to 20 V makes the current go from 0.10 A to 0.20 A. The other options would require changing the resistance or breaking the direct proportionality, which isn’t the case here.