• Resistors are passive electronic component used to limit amount of current through the circuit.
• Depending upoun value of resistance, it can be classified into two ways:
• Fixed value resistors
• Variable value resistors

-Fixed resistors are further classified into: a) Carbon composition type resistors b) Metal Film type resistors c) Wire wound type resistors a) Carbon composition type resistors:

• This is the most common type of low wattage resistor.

• The resistive material is of carbon-clay composition and the leads are made of tinned copper.

• These resistors are cheap and reliable and stability is high.

b)Wire wound resistors:

• These resistors are a length of wire wound an insulating cylindrical core.

  -Usually wires of material such as constantan (60% copper and 40% nickel) and manganin which have high resistivities and low temperature coefficients are employed. The complete wire wound resistor is coated with an insulating material such as baked enamel.

c) Metal film resistors

• It is constructed using film deposition techniques of depositing a thick film of resistive material onto an insulating substrate.

• Only approximate values of resistance can be had by this method.