Question T5A04
From subelement T5 - T5A
What are the units of electrical resistance?
Why is this correct?
Ohms (Ω) are the standard units for electrical resistance. Resistance measures how much a material opposes current flow, converting electrical energy to heat. This is a fundamental electrical unit, like volts for voltage and amperes for current. Siemens and mhos are units for conductance (the opposite of resistance), while coulombs measure electric charge, not resistance.
Memory tip
Remember the pattern: electrical quantities have their own specific units that can't be substituted. Just as you wouldn't measure distance in pounds, each electrical property has one correct unit. The ohm symbol (Ω) comes from the Greek letter omega.
Learn more
Resistance affects every circuit in amateur radio operation. Your dummy load might be 50 ohms, coaxial cable has characteristic impedance in ohms, and antenna systems are designed around specific impedance values. Understanding resistance helps you select appropriate components, calculate power dissipation in resistors, and troubleshoot circuits where excessive resistance causes voltage drops that reduce performance.
Think about it
Why do you think both resistance and impedance are measured in ohms, and how might this relationship help you understand AC circuits?