If voltage increases across a resistor with constant resistance, what happens to the current?

• A. Current increases
• B. Current decreases
• C. Current stays the same
• D. Current first increases then decreases

Answer: (A)

Current through a resistor follows Ohm’s law: I = V / R. When the resistance is constant, the current changes in direct proportion to the voltage. So increasing the voltage across the same resistor increases the current, because doubling the voltage doubles the current. For example, with a fixed 10-ohm resistor, raising the voltage from 5 V to 10 V makes the current go from 0.5 A to 1 A. Since the resistance isn’t changing, there’s no scenario where the current stays the same or decreases; the current simply increases with voltage.