resistor

INTRODUCTION
=A passive electrical component with two terminals that are used for either limiting or regulating the flow of electric current in electrical circuits.
=The main purpose of resistor is to reduce the current flow and to lower the voltage in any particular portion of the circuit. It is made of copper wires which are coiled around a ceramic rod and the outer part of the resistor is coated with an insulating paint.

TYPES OF RESISTORS
=LINEAR RESISTORS
The resistors whose values change with change in applied temperature and voltage are known as linear resistors.

1) FIXED RESISTORS
have a specific value and these values cannot be changed.
EX:
Carbon composition resistors
Wire wound resistors
Thin film resistors
Thick film resistors

2) VARIABLE RESISTORS
does not have a specific value and the values can be changed.
EX:
Potentiometers
Rheostats
Trimmers

=NON LINEAR RESISTORS
The resistor values change according to the temperature and voltage applied and is not dependent on Ohm’s Law.
EX:
Thermisters
Varisters
Photo resistors

COLOR CODING OF RESISTORS
=Resistors may not display the value outside but their resistance can be calculated through their color pattern PTH (plated-through-hole). Resistors uses a color-coding system (which really adds some flair to the circuits), and SMD (surface-amount-device) resistors have their own value-marking system.