Hi, I bought this cheap little USB multimeter/double-adapter accessory on eBay.
Today's question will be focusing on the multimeter aspect of this device.
The white USB cable is for charging the black/red Android smart-phone.
Both of which are relevant to the question.
(Unfortunately the tip of the cable is slightly damaged and may not always be making the absolute best connection.
- Apologies, it was all I had on me at the time).
If you're curious; the black USB cable is connected to a wireless network interface card.
Said interface is down, and doesn't seem to be actively consuming any resources.
It can probably be safely omitted from the scenario without affecting any other variables.
(It's main purpose here is simply to apply a small amount of physical pressure down on the white cable.
- Ensuring a decent connection, and holding it in place).
There seems to be an inversely proportional relationship between;
the potential/voltage[V] and current/amperage[A].
(At the node being measured).
##In other words:## Min current[A] = Max potential[V]; More current[A] = Less potential[V]; ##And vice versa.##
I recall being told to think of it in terms of a metaphor:
- Where electromotive-force/potential-difference[V]; is like pressure/Pascals-per-square-inch; inside a hose/pipe.
- And Coulombs-per-second/electric-current[A]; is like the flow-of-water/Litres-per-second; through said hose/pipe.
I'm not actually sure how accurate this analogy is.
But it seems to help with creating a mental image and an understanding of the mechanism of action.
- (i.e. Block the tip of a running hose; water stops flowing; you can feel the pressure build up under your thumb; the hose becomes noticeably more tense.
- Unblock the tip of a running hose; water resumes flowing; you can feel the pressure release under your thumb; the hose becomes noticeably more relaxed.)
I'm sure this is a relatively elementary question for seasoned electrical/electronic engineers/technicians, but how accurate is this analogy?
What exactly is the relationship between current and potential (as observed below)?
FYI: (I noticed that ~4.98V is approximately the maximum voltage produced by this Acer laptops buss.
Apple computers and phone-chargers (just for instance) were observed producing a more ideal maximum of ~5.11V).
Fully 'open' circuit: Not charging: [4.98V/0.00A]
Fully 'closed' circuit: Charging: [4.89V/0.30A]
Half 'open' circuit ('loose connection'): Charging ('or trying to'): [4.80V/0.14A]
Fully 'closed' circuit: Charging: [4.88V/0.27A]
Half 'open' circuit: Not charging: [4.95V/0.00A]
Fully 'closed' circuit: Charging: [4.90V/0.35A]