If a resistor in a parallel circuit has triple the resistance of a second resistor, its current is what fraction of the second resistor's current?

If a resistor in a parallel circuit has triple the resistance of a second resistor, its current is what fraction of the second resistor's current?

• A. 3/4
• B. 1/2
• C. 1/3
• D. 1/4

Answer: (C)

In a parallel circuit, the voltage across each resistor is the same, so current through each resistor follows I = V/R. If the second resistor has resistance R, its current is I2 = V/R. The first resistor has triple the resistance, so its resistance is 3R, giving I1 = V/(3R) = (1/3)(V/R) = I2/3. So the current through the first resistor is one third of the second resistor's current.

In a parallel circuit, the voltage across each resistor is the same, so current through each resistor follows I = V/R. If the second resistor has resistance R, its current is I2 = V/R. The first resistor has triple the resistance, so its resistance is 3R, giving I1 = V/(3R) = (1/3)(V/R) = I2/3. So the current through the first resistor is one third of the second resistor's current.