Question T5D10
From subelement T5 - T5D
What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?
Why is this correct?
Using Ohm's Law (E = I × R), multiply current by resistance: 0.5 amperes × 2 ohms = 1 volt. Choice B (0.25 volts) would result from dividing instead of multiplying. Choice C (2.5 volts) adds the values rather than multiplying. Choice D (1.5 volts) appears to add resistance to current, which is mathematically incorrect for this application.
Memory tip
For Ohm's Law voltage calculations, always multiply current times resistance. Remember the units help verify: amperes × ohms = volts. If your answer doesn't have volt units, you've made an operational error with the formula.
Learn more
Ohm's Law governs all circuit analysis in amateur radio operations. When troubleshooting equipment or designing antenna systems, understanding voltage drops across components helps determine power dissipation and component ratings. The relationship E = I × R applies whether you're calculating voltage drops in transmission lines, determining bias voltages in amplifiers, or sizing resistors for LED indicators in your station equipment.
Think about it
Why do you think the incorrect answers represent common mathematical mistakes students make when first learning Ohm's Law calculations?