What is a resistor?

[Sekhohub.online]

What is a resistor?

A resistor is a passive electronic component that resists or limits the flow of electric current in a circuit. It’s one of the most basic and essential components in electronics.

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Simple Definition:

A resistor reduces current flow and drops voltage in a circuit.
Think of it like a speed bump for electricity—it slows things down to protect or control other components.

⚙️Symbol in Circuit:

• In schematic diagrams:

  • U.S. symbol: 〰️ (zigzag)

  • International: ▬ (rectangle)

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Resistance and Ohm’s Law:

Resistance is measured in ohms (Ω) and follows:

$$V=I\times R$$

Where:

• V = Voltage (volts)

• I = Current (amperes)

• R = Resistance (ohms)

This is called Ohm’s Law.

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Type.

Fixed Resistor                                                    Standard, constant resistance

Variable Resistor (Potentiometer)          Adjustable resistance

Thermistor                                                       Changes resistance with temperature

LDR (Photoresistor)                                       Changes resistance with light

 

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Uses of Resistors:

• Control current in circuits

• Protect LEDs and ICs from too much current

• Divide voltage (voltage divider circuits)

• Generate heat in heaters, toasters

• Set time delay with capacitors in RC circuits

Color Code:

Resistors are marked with color bands to indicate resistance value (e.g., red-violet-yellow = 2.7kΩ).

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Summary:

• Resistor = Current limiter

• Unit = Ohm (Ω)

• Rule = Ohm’s Law (V = IR)

• Used everywhere in electronics!