/rɪˈzɪstər/
noun … “Component that limits current flow.”
Resistor is a passive electronic component that restricts the flow of electric current in a circuit, converting electrical energy into heat. Resistors are fundamental in controlling voltage, setting current levels, dividing voltages, and protecting sensitive components. They are typically made from materials with precise resistance values, such as carbon film, metal film, or wire-wound elements.
Key characteristics of Resistor include:
- Resistance value: measured in ohms (Ω), determines how much it limits current.
- Tolerance: the accuracy of the resistance value (e.g., ±1%, ±5%).
- Power rating: maximum energy it can safely dissipate without damage.
- Temperature coefficient: how resistance changes with temperature.
- Types: fixed, variable (potentiometers or rheostats), and special types like thermistors or photoresistors.
Common applications of Resistor include current limiting for LEDs, voltage dividers, signal conditioning, biasing transistors, and filtering in combination with capacitors or inductors.
Workflow example: Limiting current to an LED:
v_supply = 5 -- volts
v_led = 2 -- LED forward voltage
i_desired = 0.02 -- 20 mA
resistor_value = (v_supply - v_led) / i_desired -- Ohm's law
led.connect(resistor_value)
Here, the resistor ensures that the LED receives the correct current to operate safely without burning out.
Conceptually, a Resistor is like a narrow section of pipe in a water system: it slows down the flow, controlling how much water passes through.
See Voltage, Current, Power, Capacitor, Transistor.