I'm an automotive mechanic that specializes in electrical/drivability diagnosis. I like helping other techs get a better grasp on this aspect of our trade. Now imagine I'm with another tech and I have a battery and a multimeter in front of me. I measure the battery's voltage and get 12V.
Me: The battery is 12 volts.
Tech: Is it still 12 volts?
Me: Well, ya. I just measured it...
Tech: But V = I x R and right now it's not in any kind of circuit so shouldn't I = 0, therefore, V = 0 x R = 0..?
Me: Uhh....
I recently realized that I did not have a satisfactory answer to that. If I only responded with, "They're just different, okay? Don't ask that question and deal with it!" then I feel like I would lose significant credibility with the rest of what I say...
So, at this point, would the battery just have a voltage potential and not really a "true voltage" until it has some non zero current? Would its voltage potential really just be a manifestation of its chemical energy? But it still would have charge separation so it really should have a "true voltage" ... shouldn't it?
I'm just having a hard time getting past my discomfort with something having a non zero voltage but a zero current value. Any clarity would be greatly appreciated.
Many thanks,
Eric
Me: The battery is 12 volts.
Tech: Is it still 12 volts?
Me: Well, ya. I just measured it...
Tech: But V = I x R and right now it's not in any kind of circuit so shouldn't I = 0, therefore, V = 0 x R = 0..?
Me: Uhh....
I recently realized that I did not have a satisfactory answer to that. If I only responded with, "They're just different, okay? Don't ask that question and deal with it!" then I feel like I would lose significant credibility with the rest of what I say...
So, at this point, would the battery just have a voltage potential and not really a "true voltage" until it has some non zero current? Would its voltage potential really just be a manifestation of its chemical energy? But it still would have charge separation so it really should have a "true voltage" ... shouldn't it?
I'm just having a hard time getting past my discomfort with something having a non zero voltage but a zero current value. Any clarity would be greatly appreciated.
Many thanks,
Eric