# Resistors

#### Introduction to Resistors

• resistor is a two-terminal device that is used to resist the flow of current. It is one of the most commonly used components in electrical circuits.
• Resistance of any resister is described in ohms. Ohm is denoted by the Greek letter omega. Each resister has a different value of resistance which tells us how strongly it resists the flow of current. More the value of resistance more is the capability of resisting the current.
• Resistance will be considered as one ohm if the potential difference between the two ends of the conductor is 1 V and a current flowing through it is 1 Ampere.
• Resistance can be derived from Ohm’s law which indicates voltage is directly proportional to the current flowing through the conductor.

V= I * R

• Each resistor comes with two wires, also called as leads. Between these two leads there lies a ceramic part which actually resists the flow of current.
• Resistor consists of three colored strips that indicate the value of resistance.
• Some resistors come with four colored strips. In such case, fourth strip indicates the value of tolerance. Tolerance is the value of the deviation of resistance from its given value on the resistor. Gold color of forth strip indicates tolerance is 5% and silver color indicates tolerance is 10%. Where there is no forth strip, tolerance is considered as 20%. Suppose, if resistance has 50-ohm resistance with no forth strip. Then tolerance of such resistor can be 50 ±20%.
• Resistors also indicate temperature coefficient. Temperature coefficient is known as a resistance due to the change in temperature. There are two types of temperature coefficients. Positive temperature coefficient and negative temperature coefficient. If resistance increases with the increase in temperature then it is called positive temperature coefficient and if resistance decreases with the decrease in temperature then it is called negative temperature coefficient.

#### How to Calculate Resistance of any Resistor

There are two different ways to calculate the resistance: