Voltage Divider Calculator for 3 Resistors

Voltage divider calculator for 3 resistors lets you calculate the voltage divided by three series resistors.

voltage-divider-calculator-for-3-resistors

Instructions:

  1. Enter the input voltage.
  2. Enter resistance of first resistors.
  3. Enter resistance of the second resistor.
  4. Enter resistor of the third resistor. (The default input for all resistors are in ohms)
  5. The default voltages are provided with an accuracy of two decimals.

Formula:

V1 = { R1 / (R1 + R2 + R3) } * Vin

V2 = { R2 / (R1 + R2 + R3) } * Vin

V3 = { R3 / (R1 + R2 + R3) } * Vin

Let’s solve an example to understand it:

Example # 1: For the circuit diagram shown above, determine the potential dropped across three resistors if R= 50 Ω, R= 100 Ω and R= 50 Ω. The input source is a 12 V dc battery

Solution:

V1 = { R1 / (R1 + R2 + R3) } * Vin = { 50 Ω / ( 50 Ω + 100 Ω + 50 Ω) } * 12 V = 3 V  

V2 = { R2 / (R1 + R2 + R3) } * Vin = { 100 Ω / ( 50 Ω + 100 Ω + 50 Ω) } * 12 V = 6 V

V3 = { R3 / (R1 + R2 + R3) } * Vin = { 50 Ω / ( 50 Ω + 100 Ω + 50 Ω) } * 12 V = 3 V

Let’s solve another example with different values of resistors.

Example # 2: For the same previous circuit, determine the voltage that is dropped across three resistors if their values are R= 10 Ω, R= 1 kΩ and R= 5 kΩ. The input source is a 10 V dc battery. Compare the example with previous one and generalize your observations for any voltage divider circuit.

Solution:

V1 = { R1 / (R1 + R2 + R3) } * Vin = { 10 Ω / ( 10 Ω + 1 kΩ + 5 kΩ) } * 10 V = 0.016 V  

V2 = { R2 / (R1 + R2 + R3) } * Vin = { 1 kΩ / ( 10 Ω + 1 kΩ + 5 kΩ) } * 10 V = 1.663 V

V3 = { R3 / (R1 + R2 + R3) } * Vin = { 5 kΩ / ( 10 Ω + 1 kΩ + 5 kΩ) } * 10 V = 8.319 V

Also try our simple VDR calculator and loaded VDR calculator.

There are some observations from both cases:

  1. The sum of individual voltages V1, V2, and Vis equal to overall input.
    • Case 1: Vin = V1 + V+ V3= 3 V + 6 V + 3 V = 12 V
    • Case 2: Vin = V1 + V+ V3= 0.016 V + 1.663 V + 8.319 V = 10 V
  2. The larger the magnitude of resistor, the greater potential drop has it.
    • Case 1: R2 > R1 > &  R2 > R3  ,  V2 > V1 > &  V2 > V
    • Case 2: R3 > R2 > R1  , V3 > V> V1
  3. A very small resistor has negligible voltage dropped across it as compared to a very large resistor.
    • Case 2: Likewise R3 is 500 times greater than R31, the V3 is also very large as compared to V1.
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