A: most of the time it will be written/printed on the potentiometer, for example it might say "10K". This indicates it is a 10kOhm pot. However sometimes it's not. Get out your multimeter, and set it to the ohm/resistance setting. Set it to the lowest (smallest) to begin with... eg: 10ohms, as opposed to 10MOhms. Now, turn the knob on the pot all they way to one side - doesn't matter which way you turn it. Now, touch one probe onto the middle pin of the pot, and then touch the other probe onto one of the outer two pins - only one - and it doesn't matter which one (I know, choices are tough ) If the multimeter reads "0.00", then start turning the pot, and you should see the number increase. When you have turned the knob all the way to the other side, the value should be at it's maximum, and this is the rating of the pot. Note: it is likely that you will have to change the setting on the multimeter, for example, if the pot is 10kohm, you won't get a succesfull reading if you have it set to 10ohm's max. Start with a low setting, and turn it up if needed.