Voltage Divider And Current Divider Rules

Voltage Divider And Current Divider Rules

Voltage divider and current divider are one of the basic circuits in electronic. They are very useful principle in the building of real world products. Many electronic/electrical devices operate on this principle. In order to understand and solve calculation problems based on voltage divider and current divider; you must know:

In this article you will learn:

  • What voltage divider and current divider are.
  • How to solve problems on voltage divider and current divider

Voltage divider

Voltage divider is a simple circuit which turns a huge voltage into smaller ones to different parts of the circuit. This occurs by suppling of voltage source to two or more resistors connected in series.

Calculations On Voltage Divider

Voltage divider

Find the voltage in each resistor in the circuit.

There are two methods to find the voltage in each resistor in the above series circuit.

Method1

First you have to the current ‘I’ flowing in the circuit.

From Ohm’s law ‘V=I×Rt’ where

V is input voltage= 12V

Rt is the total equilivalent resistors in the circuit connected in series=6

Since the same amount of current flows through the resistors,

Therefore I=12/6 ; I=2A

Now,let’s find the voltage(output voltage) in each resistor

From Ohm’s law formula V=IR, let V1,V2,V3 represent the voltage in resistors 1,2 & 3.

V1=I×R1; V1=2×1=2V

V2=I×R2; V2=2×2=4V

V3=I×R3; V3=2×3=6V

 

Method2

Formula method

Vx=Vt*Rx/Rt

This formula is derived from the first method.

Where Vx is output voltage (V1,V2,V3…..)

Vt is input voltage, that is the total voltage

Rx is the individual resistor in the circuit (R1,R2,R3……)

Rt is the equilivalent resistors in the circuit

V1=Vt×R1/Rt; V1=12×1/6=2V

V2=Vt×R2/Rt; V2=12×2/6=4V

V3=Vt×R3/Rt; V3=12×3/6=6V

Very easy isn’t it?

Voltage divider

Summary of how the voltage is divider among the resistors

 

 

 

 

 

 

 

Derivation Of The Formula Method

Input voltage

Vt=I×Rt; I=Vt/Rt..……..(1)

 

Output Voltage

Vx=I×Rx; I=Vx/Rx……(2)

Since current flowing through the resistors is the same.

Therefore I=I; Vt/Rt=Vx/Rx

Vx=Vt×Rx/Rt

 

Current Divider Rule

A current divider circuit is a circuit which divides the large current from the power source into smaller amounts to different parts of the circuit. This occurs only in circuits with two or more resistors connected in parallel.

Calculations On Current Divider

Current Divider Rule

Find the current in each resistor in the circuit.

 

 

There are also two methods to find the current flowing in each resistor in the parallel circuit above.

Method 1

From Ohm’s law  V=Ix×Rx where

Rx  can be R1,R2,R3……. and Ix can be I1,I2,I3…….

Since voltage is the same in all resistors,therefore

I1=V/R1; I1=12/2=6A

I2=V/R2; I2=12/4=3A

I3=V/R3; I3=12/2=2A

 

Method 2

Formula method

Ix=It×Rt/Rx where It is the total current flowing in the circuit.

From V=It×Rt; It=V/Rt

Rt=1.09 Ohms (value of equivalent resistors in parallel)

Therefore: It=12/1.09= 11A

I1=It×Rt/R1 ; I1=11×1.09/2= 6A

I2=It×Rt/R2 ; I2=11×1.09/4= 3A

I3=It×Rt/R3 ; I3=11×1.09/6= 2A

Derivation Of the Formula Method.

From input voltage:

V=It×Rt………(1)

Output voltage

V=Ix×Rx……(2)

Since input and output voltage is the same for resistors in parallel.

Therefore output voltage=input voltage V=V

Ix×Rx=It×Rt

Ix=It×Rt/Rx

 

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