# Determine Voltage Drop Across Resistors

How to calculate voltage drop across series resistors.

1. How to calculate voltage drop across series resistors.

Step 1

Determine current of total resistors across the series.

(I = Current/V=Voltage/R(t)=Resistance Total)

I = V / R(t)
I = 9 / (2k + 5k + 10K)
I = .53 mA​

Step 2

Now that we have the Current across the resistors we can calculate the voltage across EACH resistor.

I = Current
Vx = Voltage (x = Current Value across X Resistor)
Rx = Resistor value(x = resistor#)

V = I x Rx

V1 = .53 mA x 2k
V1 = 1.06V

V2 = .53 mA x 5k
V2 = 2.65

V3 = .53 mA x 10k
V3 = 5.3V

V1 + V2 + V3 = 9.01 (voltage is 9V only 9.01 because i rounded up from .529 to .53) At .529 you can see barely a difference:

V1=1.058V
V2=2.645V
V3=5.290V
V Total= 8.993V​

Also If the resistors are all the same value its easier.

I = V / R(t)
I = 9 / (5k + 5k + 5K)
I = .6 mA

THEN:

V = I x Rx

V1 = .6 mA x 5k
V1 = 3V
so since all Resistors are same value:
V2 = 3V
V3 = 3V

Also To get different values for like switches just use gnd as a start point and the end of each resistor and a end point. This way you get 3 switches from this each having different voltages

SW1 = 3V
SW2 = 6V
SW3 = 9V

So I hope someone can learn something from this.

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