In a circuit with a fixed voltage, what is the effect of increasing a resistor's resistance on the current?

• A. The current increases
• B. The current remains the same
• C. The current decreases
• D. The current doubles

Answer: (C)

Ohm's law shows that in a circuit with a fixed voltage, current is inversely proportional to resistance. I = V/R means that when the voltage stays the same and resistance increases, the current must fall. So increasing a resistor’s resistance makes it harder for charges to flow, and fewer charges pass per second. For example, doubling the resistance with the same voltage would halve the current. The current does not stay the same and it does not automatically double—that would only happen if the voltage changed or the resistance changed in a different way.