Voltage dividers confusions

MrChips

Joined Oct 2, 2009
30,711
You can look at it from either perspective. Both are correct.

There is a voltage V1 across R1.
There is also a voltage V2 across R2.

You can write all sorts of equations.
V1 = I x R1
V2 = I x R2
Vin = V1 + V2
I = Vin / ( R1 + R2)

Vout = V2 = Vin - V1 = Vin x R2 / (R1 + R2)

1577335321406.png

All of the equations are consistent with the concept of a voltage divider as shown.
 

Wolframore

Joined Jan 21, 2019
2,609
You can also look at it this way...

total current is calculated by adding up both resistors.

I= V/(R1+R2)

that same current goes through each resistor
the voltage dropped at each resistor is

VR1= I x R1
VR2=I x R2

therefore the voltage between them is whats dropped by R2

the proper formula is
(R2/(R1+R2))VCC

so the resistors form a ratio.
 
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