555 Timer LED Flasher - What is Resistor ?


    • Resistors are a specific, never-changing electrical resistance.
    • Resistors are electronic components
    • The resistor’s resistance restricts the flow of electrons through a circuit.
    • Resistors are common elements of electrical networks and electronic circuits and are global in electronic equipment.
    • Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits.


    • Variable resistors are called potentiometers
    • There is a fixed value of resistance between two terminals
    • The moving part of the potentiometer is called the wiper.
    • Four band resistor colour code
      • 1st band provides the first digit of the code
      • 2nd band provides the second digit of the code
      • 3rd band is the multiplier
      • 4th band indicates the tolerance value


    Resistor colour code calculation

    • The first band red has a value of 2
    • The second band purple has a value of 7
    • The third band has a multiplier of x 10
    • The last band indicates a tolerance value of +/-5%
    • Resistance value is 270Ω +/-5%

    Ohm's law

      • The behaviour of an ideal resistor is dictated by the relationship specified by Ohm's law:
       v = I.R
      • Ohm's law states that the voltage (V) across a resistor is proportional to the current (I), where the constant of proportionality is the resistance (R).

      Series and parallel resistors

        • The total resistance of resistors connected in series is the sum of their individual resistance values.
         Serial Resistors

        Serial Resistors

        • The total resistance of resistors connected in parallel is the reciprocal of the sum of the reciprocals of the individual resistors.
         parallel Resistor

        parallel Resistor

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