Voltage Divider Calculator & Formulas for Resistor Voltage Divider

by Neon Sunday, October 04, 2020 Post a Comment

The Voltage Divider formula is a basic formula that you must learn. With this formula, there will be many projects that you can create. This article will explain how the resistor voltage divider occurs and the formula and the Voltage Divider Calculator.

Figure 1 Voltage Divider Calculator (left) and Voltage Divider Circuit (right)

A series resistor circuit acts as a voltage divider. You will learn what a voltage divider is and why it is such an important application in series circuits.

To understand the basics of the middle divider resistor series circuit, you can look at the following image of the voltage divider circuit, where there are two resistors connected in series.

In the picture of two resistors connected in series above, there will be a voltage drop or voltage drop on each resistor (R1 and R2).

2 The position of this voltage drop is labeled V1 and V2 or usually labeled Vout1 and Vout2.

since each resistor has the same current through it, the voltage drop is proportional to the resistance value.

For example, if the divider resistor value R2 is twice as large as R1, then the value of V2 will be twice as large as V1.

With some calculations, a formula can be determined how the voltage is divided between the series resistors made.

Voltage divider formula (resistor voltage divider)

Let's make the term the voltage drops of each resistor Vx, where x represents the number of a particular resistor.

With Ohm's law, the voltage drop across each resistor and the equation can be written:

Vx = I.Rx

where x is R1, R2, R3, R4, R5 or others depending on the number of resistors in your circuit.

Also according to ohms law, current equals the source voltage divided by the total resistance. Then the equation:

I = Vs / Rtotal

Then, substituting Vs / Rt for I in the Vxi.Rx expression yields:

Vx = (Vs * Rx) / Rtotal

The principle of the voltage divider is that the voltage drop across a resistor or resistor combination in a series circuit is equal to the ratio of the value of its resistance to total resistance, multiplied by the source voltage.

A. Example problems and solutions

The following is an example and solution for dividing the resistor voltage with two series resistors. This formula is the basic formula for Ohm's law.

If you don't understand the Ohm's law formula, you can read the article here. There is also a calculator for Ohm's law.

1. The first example

If you know Vs, R1 and R2, how do you find Vout1 and Vout2?

Answer:

First find the current I first because the currents in the series resistor are the same. The formula is I = Vs/ (R1 + R2)

Second look for Vout1. The formula is Vout1 = I.R1

Third, look for Vout2. The formula is Vout2 = I.R2

2. The second example

If Vs, Vout1 and Vout2 are known, how do I find R1 and R2?

Answer:

Since R1 and R2 are not known, the only way is to determine the Rtotal. For example, we determine that the total is 2K Ohm.

First look for current I first. I = Vs / 2K

Second, find the resistance R1, the formula is R1 = (Vs- Vout1) / I

Third, find the resistance R2, the formula is R2 = (Vs - Vout2) / I

B. Resistor Voltage Divider Calculator

To make calculations faster, I made a simple voltage divider calculator with two resistors in Series.

With this calculator you can get the value of the output voltage, or the resistance used or the total voltage.

Feel free to experiment with the following calculators: