RESISTOR

 RESISTOR 

Resistor is determine the flow of current in an electric circuit.the higher the resistance in the circuit,the smaller is the current in it and vice versa.  resistance is measured in ohms.

All modern fixed value Resistor can be classified into four broad groups:

Symbol 

1.carbon composition resistor:carbon composition Resistor is manufactured from a mixture of finely ground carbon dust graphite and a non conducting ceramic  power to bind it all together. These are usually low wattage Resistor. 

2.Firm Resistor firm Resistor consists of metal film,carbon film and metal oxide film Resistor types.these Resistor are made by depositing pure metals,such as nickel,or an oxide film,such as tin oxide,onto an insulating ceramic rod,or substrate made from conductive metal oxide paste.these are also low wattage Resistor 

2.thick film Resistor are made by depositing a much thicker conductive paste of ceramic and metal called Carmen,onto an alumina ceramic substrate. 

3.wire wound ResistorResistor:wire wound Resistor is made by winding a thin metal alloy wire such as Nichole into an insulating ceramic former in the form of a a spiral helix.these types of Resistor are generally only available from few ohms to typically 100ohms.

4.semiconductor resistor:semiconductor Resistor is derived from a doped semiconductor material. In fact ,some of the active devices that will be discussed later will be replacing Resistor in the manufacture of integrated circuits. 

Example problems 

1.for the circuit indicated Resistor values, calculated resistance?

Answer:

R=R1+R2+R3

R=200+300+500

R=1000ohms