The components which resist or oppose the flow of electrons in any electrical or electrical circuit is called resistor. The force by which it resists flow of current is called resistance. It is measured in Ohms (Ω). Resistors are used to limit current flowing through a circuit or to divide the voltage in a circuit.
Types of Resistors
i) Fixed Value Resistors.
ii) Variable Value Resistors.
Fixed Resistors: The Resistors whose value remain same and can’t be changed is called fixed value resistor. Fixed value resistors can be of following types:
a) Carbon Resistors: These types of Resistors are manufactured from mixture of carbon or graphite and clay. These are also made in metalized type by decomposing a homogeneous film of pure carbon or metal over glass, ceramic or any other insulating core.
b) Wire Wound Resistors: These types of resistors are made
for higher power ratings. It consist of a high resistance material wire that is wrapped around a hallow porcelain cylindrical core. Nichrome, Tungsten, Manganin like material are used as high resistance wire. Both the ends are attached to a metal piece. This assembly is than coated with enamel containing powder glass. This coating is than heated to develop a vitreous enamel which provides mechanical strength to resistance wire. Resistivity is totally dependent on the material used for making resistance.
Variable Resistors: The resistors whose value can be changed to adjust the value of current or voltage are called as variable resistors. These are also known as Potentiometers, Rheostats or simply pots. These Types of Resistors can be further classified into two categories.
a) Carbon Composition of Variable Resistors: It consists of a carbon composition resistance disc. Disc’s two ends are connected to external soldering lugs. It also consists of a third rotating shaft at the centre which is also connected to third external soldering lug. The rotating shaft makes contact with carbon disc at different points to give different output resistance.
b) Wire Wound Variable Resistors: In this type of resistors high resistance wire is wound over dough shaped core .This core can either of Bakelite or ceramics. There is a central shaft at core’s centre. Three terminals come out from resistor/Potentiometer. Outer two ends are points of resistance element and third (central) is rotating contact.
Types of Resistors
i) Fixed Value Resistors.
ii) Variable Value Resistors.
Fixed Resistors: The Resistors whose value remain same and can’t be changed is called fixed value resistor. Fixed value resistors can be of following types:
a) Carbon Resistors: These types of Resistors are manufactured from mixture of carbon or graphite and clay. These are also made in metalized type by decomposing a homogeneous film of pure carbon or metal over glass, ceramic or any other insulating core.
b) Wire Wound Resistors: These types of resistors are made
for higher power ratings. It consist of a high resistance material wire that is wrapped around a hallow porcelain cylindrical core. Nichrome, Tungsten, Manganin like material are used as high resistance wire. Both the ends are attached to a metal piece. This assembly is than coated with enamel containing powder glass. This coating is than heated to develop a vitreous enamel which provides mechanical strength to resistance wire. Resistivity is totally dependent on the material used for making resistance.
Variable Resistors: The resistors whose value can be changed to adjust the value of current or voltage are called as variable resistors. These are also known as Potentiometers, Rheostats or simply pots. These Types of Resistors can be further classified into two categories.
a) Carbon Composition of Variable Resistors: It consists of a carbon composition resistance disc. Disc’s two ends are connected to external soldering lugs. It also consists of a third rotating shaft at the centre which is also connected to third external soldering lug. The rotating shaft makes contact with carbon disc at different points to give different output resistance.
b) Wire Wound Variable Resistors: In this type of resistors high resistance wire is wound over dough shaped core .This core can either of Bakelite or ceramics. There is a central shaft at core’s centre. Three terminals come out from resistor/Potentiometer. Outer two ends are points of resistance element and third (central) is rotating contact.
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