/rɪˈzɪstəns/
noun … “Opposition to the flow of electric current.”
Resistance is a property of a material or component that limits the flow of current when a voltage is applied. It is a fundamental concept in electricity and circuit design, affecting power consumption, heat generation, and signal behavior in electronic systems.
Key characteristics of Resistance include:
- Unit: measured in ohms (Ω).
- Ohm’s law: R = V / I, relating voltage (V), current (I), and resistance (R).
- Dependence on material: metals, semiconductors, and insulators have differing resistance levels.
- Temperature effects: resistance often increases with temperature for conductors and decreases for some semiconductors.
- Applications: resistors control current, divide voltages, protect components, and shape signals.
Workflow example: Calculating current through a resistor:
voltage = 12 -- volts
resistor = 1000 -- ohms
current = voltage / resistor
print(current) -- 0.012 A
Here, the resistor limits current flow according to Ohm’s law.
Conceptually, Resistance is like friction in a pipe: it resists the flow of water (charge) and determines how easily it moves through the system.
See Current, Voltage, Power, Ohm, Electricity.