Question T5D11
From subelement T5 - T5D
What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?
Why is this correct?
The correct answer is 10 volts (B). Using Ohm's Law, E = I × R, where E is voltage, I is current, and R is resistance. Substituting the given values: E = 1 ampere × 10 ohms = 10 volts. Option A (1 volt) would result from multiplying 1 × 1, confusing the resistance value. Options C (11 volts) and D (9 volts) come from incorrectly adding or subtracting the values instead of multiplying.
Memory tip
When applying Ohm's Law, always identify which variable you're solving for, then use the appropriate rearrangement. The circle diagram technique helps: cover the unknown value, and the remaining positions show whether to multiply or divide the known values.
Learn more
In practical amateur radio circuits, this relationship is fundamental for antenna system calculations and power supply design. When you increase current through a fixed resistance, voltage drop increases proportionally. This affects transmission line losses, impedance matching networks, and amplifier bias circuits. Understanding voltage drops across circuit elements helps troubleshoot equipment performance and ensures proper operating parameters for transceivers and linear amplifiers.
Think about it
Why do you think voltage increases proportionally with current when resistance stays constant, and how might this principle help you diagnose problems in your radio equipment?