# What is Resistor?

A resistor is a passive electrical component that induces electrical resistance in a circuit. In electronic circuits, resistors play various roles. It is used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses.

The resistive element is made from a mixture of carbon powder and an insulating material, usually ceramic. A resin holds the mixture together. The resistance is determined by the ratio of the fill material (the powdered ceramic) to the carbon. The resistance rating was then painted as color-coding that indicates its value.

## What does it do?

The ability to resist current is known as resistance. And it is measured as OHM.

We can obtain the relationship between voltage, current and resistance from ohm’s law. That states,

The resistor’s current I flows through the resistor in amps (A) is equal to the voltage V across the resistor terminals in volts (V) divided by the resistance R in ohms (Ω)

i.e. R = V/I

We know the power P consumes by a circuit is equals to total Current I times voltage V

Or, P=V*I

Therefore The resistor’s power consumption P in watts (W) is equal to the square value of the resistor’s current I in amps (A) times the resistor’s resistance R in ohms (Ω)

P = I²R

or, P =V²R

## How does it work?

The resistors often come with specific resistance ratings. Now, if we need some other values than the standard value available we can connect multiple resistors in either series or parallel configuration

### Series Resistance:

A series resistance is formed by connecting 2 or more resistors in series. In this configuration, the total resistance has become the sum of the individual resistors. For example, if we take three resistors of values R1, R2 and R3 the series resistance will be,

R = R1 + R2 + R3

So when you connect resistors in series the equivalent resistance increases.

### Parallel Resistance:

Similarly when you connect multiple resistors in parallel to one another it forms a parallel resistance circuit. Resistors are in parallel if their terminals are connected to the same two nodes. Here The sum of the currents through each path is equal to the total current that flows from the source. You can find total resistance in a Parallel circuit with the following formula:

1/Rt = 1/R1 + 1/R2 + 1/R3

So when multiple resistors connected in parallel configuration the equivalent resistance decreases

## Where to use it?

Resistors have many applications in an electronic circuit. It is used in series with LEDs to limit the current flows through that LED. A typical LED requires 30mA to work properly. Adding a current limiting resistor will provide overcurrent protection.

Resistors are also used as lower voltage levels when two resistors connected in parallel configuration become a voltage divider to decrease the voltage potential.

A resistor is also used as to pull up or pull down some certain logic signals if they requires not to left floating