This article explains resistors and types of resistors.
Resistors are passive two-terminal electronic components that offer electrical resistance or opposition to flow of current in a circuit. Resistors reduce current flow and also they lower voltage in an electronic circuit.
Mixture of carbon or various compound and films are use for constructing them. Also, they are as well constructed from resistance wires. That is; wire made of a high-resistivity alloy, such as nickel-chrome. Constantan, manganin, and nichromes wires are also use when high resistance is needful in a circuit.
UNITS OF RESISTORS
Ohm (Ω) is the standard International (S.I) unit of Resistor, named after the German Physicist George Simon Ohm (1787 – 1854). Other units are include; milliohm (mΩ= 10-3); Kilohm (KΩ = 103); and Megohm (MΩ = 106).
DEMONSTRATION OF HOW RESISTOR AFFECTS FLOW OF CURRENT IN CIRCUITS
From the four (4) diagrams below (A – D), is shown that the higher the resistance of the conductor, the lower is the flow of current through it. And also, the lower the resistance of the conductor, the larger is the flow of current through the conductor.
TYPES OF RESISTOR
Resistors are of different types. There are different designs in which resistors come with although, they all serve the same purpose. That is; offering electrical resistance or opposition to flow of current in a circuit with a certain resistance.
Resistors can be classified into three types. That is;
- Fixed Resistors
- Rheostat Resistors (Variable Resistors)
- Potentiometer Resistors
Standard resistors are other names of the fixed resistors. They are mostly made by measured lengths of resistance materials. Such wires are as manganin, or constantan wires cut out and wind on either a cardboard or wood and with a provided terminals for connection.
The figure below shows the circuit symbols which represent Fixed Resistor
RHEOSTAT RESISTORS (VARIABLE RESISTORS)
As opposed to the fixed resistors, rheostat or variable resistors are however the types in which their resistance values can be varied. That is, their resistance values are not fixed. They can still be used as a rheostat or variable resistor only if the first or the third and the second (middle) terminals are used.
The figure below shows the circuit symbols which represent Rheostat Resistor (Variable Resistor)
This type of resistors has three terminals which come with either a sliding or rotating contact point. They are mostly use to form a voltage divider.
The figure below shows the circuit symbols which represent Potentiometer Variable Resistor