how to Find Change in Current?

Hi! there are some sensors, whose outputs variation is 4-20 mA. My question is how to find this variation through Arduino ?

Plz Help me...ASAP :(



Try this link

You can set up a resistor and measure the voltage drop across the resistor then use simple V=IR to find current.

This sounds like a current loop output. Is it a passive one or active one. That is does it actually generate a voltage and will produce a voltage if a resistor is connected across it. Or is it just a load that when you put a voltage into it will draw the current.