A resistor is a conductor used in a circuit that has a known value of resistance. Resistors come under passive electronic components and are extensively used in electronic circuits. So important are these components that it may be virtually impossible to build an electronic circuit without involving resistors. Basically the function of a resistor is always to oppose the flow of current through it and the strength of this opposition is termed as its resistance.
The main objective of using resistors is to control the quantity of the =Tent flowing in a circuit. There are two types of resistors that are used in a circuit. These are:
- Fixed resistors
- Variable resistors
Fixed resistors: The fixed resistors are those who have fixed values of resistance. The fixed resistors that are generally used in laboratory are shown in figure.
Variable resistors: The variable resistors are those whose value of the resistance can be changed according to the necessity. These are called rheostat too. A rheostat is included in a circuit to vary the current flowing through it.
