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If you have ever built a circuit, then you might have come across this component, this is a resistor. So how does it works let’s find it out!

### What is a Resistor

A resistor is an electrical component that resists rate of flow of current and unit of resistor is Ohms.

it is represented by two symbols show above.

Ohm’s law

The current I is equal to the voltage V divided by the resistance R

also represented by V=I*R

### Resistors in Series

The equivalent resistance of resistors in series is the sum of the resistance values:

Req= R1+ R2+ R3+…

Therefore equivalent resistance increases

### Resistors in Parallel

The equivalent resistance of resistors in parallel is given by:

(1/Req)=(1/R1)+(1/R2)+(1/R3)+…

Therefore equivalent resistance decreases

### Voltage Drop

This happens when resistors are connected in series and the drop in the voltage can be calculated using the formula

V1=(R2*V)/(R1+R2)

### Power Ratings of Resistor

There are various types of resistor such as Shunt, Power, Variable etc.

But most importantly Power rating is a crucial factor while designing the circuit or else You can see what can happen in the circuit in this Video.

### How to use a resistor

If we want to power a LED which requires 3V and 20 mA to operate and we want to power it using 9V battery, then we need a resistor otherwise LED will get damaged instantly because of excess current. The value of the resistance can be calculated using the ohms law, which says voltage equal to current times resistance. So our voltage is 9V and current is 20mA so resistance value comes out to be 450 ohms but I have 1k ohm resistors so I will add 2 of them in parallel so equivalent resistance becomes 500 Ohms.