Resistance and Resistivity

[Diarmuid1]

Hi,

I am looking for information, on how to calculate the resistance I need, for example If I had, the voltage I wanted to put in, and the voltage I wanted it to put out, how would I calculate the resistance needed?

Thanks

Diarmuid

 

[audioguru2]

If the input voltage and the load's current never change (they nearly always change) then simply use Ohm's Law to calculate the resistance.

 

[Staigen1]

Hi Diarmuid

Then you have to learn Ohms Law! It goes like this:

 

[Diarmuid1]

Thanks for all your help so far.

I am guessing that R, is resistance, but what do U and I stand for?

Thanks very much

Diarmuid

 

[Staigen1]

Hi

U stands for Voltage and I stands for Current, but
Dont you think its time to read a beginner's book about elektronics first?


//Staigen

 

[Diarmuid1]

yeah, I suppose it is.

I'll try and get one today, from amazon.

thanks

Diarmuid

 

[Staigen1]

Hi Diarmuid

There are already some good books here on this site, E-Books(PDF-files, some are RARed)!
Look at the "Articles" area at the top of this side! Ante have uploaded some too,
look in the "Electronic Resources" area here in the forum! They dont cost you a lot!

//Staigen

 

[MP1]

Hi,

I am looking for information, on how to calculate the resistance I need, for example If I had, the voltage I wanted to put in, and the voltage I wanted it to put out, how would I calculate the resistance needed?

Thanks

Diarmuid

Diarmuid,
From your post, it sounds as if you are looking for a resistive voltage divider.
Here is a nice illustrated link that will explain how to do this.

http://physics.mtsu.edu/~phys2020/Lectures/L12-L16/L13/Volt_Divider/volt_divider.html
Hope this helps.

MP