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Resistors Track and electrical/DCC
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Super User 685 posts BR GP30 2300 Super User 685 posts
BR GP30 2300

Hi,

If you have a 12.5 volt source......and you put in a 1K ohm resistor.......shouldn`t the voltage drop below 12.5 volts?
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UPWilly Prolific poster 1,968 posts
UPWilly

Retraction

Sorry - Mr. Schmidt has opined that I was not correct in my explanation. As such, I respectfully retract my previous comment posted in this reply.

 

Bill D.

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LKandO Prolific poster 3,839 posts
LKandO

It does, you just have no place to measure it

Quote:

shouldn`t the voltage drop below 12.5 volts?

Depends upon where you measure.

With a single resistor across the 12.5v then the resistor is dropping the full 12.5v so there are no points to measure the voltage that won't show the full 12.5v.

If you have two resistors then yes you can measure less than 12.5v. It's called a voltage divider circuit.

_divider.png    b59980f0.png 

Alan

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pschmidt700 Prolific poster 2,584 posts
pschmidt700

Voltage divider

And the function of a voltage divider is where you overstated things somewhat, UPWilly! Resistors in a voltage divider do not change the amount of current, because current is constant in a series circuit (restatement of Kirchhoff's Current Law). They do reduce (drop) voltage, providing a predictable amount of voltage at each node in the voltage divider (Kirchoff's Voltage Law restated). Paul Schmidt
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