Question T5D12
From subelement T5 - T5D
What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it?
Why is this correct?
The correct answer is D (20 volts). Using Ohm's Law, E = I × R, where E is voltage, I is current, and R is resistance. Substituting the values: E = 2 amperes × 10 ohms = 20 volts. The wrong answers result from calculation errors: A (8 volts) subtracts instead of multiplying, B (0.2 volts) divides current by resistance instead of multiplying, and C (12 volts) adds the values instead of multiplying them.
Memory tip
For Ohm's Law voltage calculations, always multiply current times resistance (I × R). The units help verify: amperes × ohms = volts. If your calculation gives a voltage much smaller than the resistance value when current is greater than 1 amp, you've likely divided instead of multiplied.
Learn more
Voltage drop across a resistor represents the electrical potential difference caused by current flowing through resistance. In practical circuits, this voltage drop is what causes power dissipation as heat. Higher current through the same resistance creates proportionally more voltage drop, which is why high-current circuits require careful voltage regulation and appropriate conductor sizing to handle the increased electrical stress.
Think about it
Why do you think the voltage across a resistor increases linearly with current, and what would happen to circuit operation if this relationship weren't predictable?