knowverseQuestion 1
What is the unit of resistance?
Resistance is measured in ohms.
Source excerpt
The standard unit for measuring this opposition is the Ohm, represented by the Greek letter Omega ($\Omega$).
From the Knowverse course text.
Read more about the topic
Voltage, current and resistance
Resistance describes opposition to electric current and is measured in ohms. Resistivity is a material property, while the resistance of a particular wire also depends on its dimensions. A longer wire has more resistance than a shorter wire of the same material and cross section. Thickness and temperature can matter too.
For an ohmic component under steady conditions, voltage equals current multiplied by resistance: V = IR. Keeping resistance fixed, increasing voltage increases current. Keeping voltage fixed, increasing resistance reduces current. This relationship helps calculate unknown quantities, but components that heat substantially or behave nonlinearly need a more careful model.
Source excerpt
This formula tells us that Voltage is the result of multiplying the Current by the Resistance.
From the Knowverse course text.
Power and component values
Electrical power is the rate of energy transfer, measured in watts. In a simple DC circuit, power equals voltage multiplied by current. For a resistor obeying Ohm's law, this also gives P = I²R. The energy transferred depends on how long that power is supplied, so watts and watt-hours describe different quantities.
A fixed resistor has a nominal resistance and a tolerance describing permitted variation. A potentiometer provides an adjustable contact on a resistive track. On a four-band resistor, two bands give digits, a third gives the multiplier and the final band gives tolerance. Reading the band roles together identifies the marked value.
Source excerpt
The fourth and final band is usually spaced slightly further apart. This is the Tolerance band.
From the Knowverse course text.