It seems to me to happen all the time: I’ll buy a soda at a fast food place, where the cup is made of plastic. I’ll fill it with soda at a fountain. I’ll start to sip…and get a tiny little zap on my lip.
Is this just a static electric spark, same as you get when shuffling across a carpet and touching a doorknob? Is the electricity accumulated from the carbonated water running through the nozzle? Have I just re-discovered the Leyden Jar?
At first, I thought it was a chemical thing, perhaps the salt on my lip popping a CO2 bubble. But it seems always to happen only with the first sip, so static electricity is now my leading guess.
Well, that’s interesting.
Foam cups are very good insulators.
If you generated a static charge by walking across the floor, and then filled the cup without touching the dispenser with your hand, I could see how the liquid in the cup might be charged relative to your body, and give a small shock.
I have noticed this too. No real answer, but…
I occasionally have McDonalds for lunch, but for health reasons (ha!), get an apple juice and a cup for water.
I get a tiny shock the instant the water contacts my lip, so I’ve eliminated the possibility that it has anything to do with carbonation.
Does water acquire an electric charge from flowing through a nozzle? Sort of like brushing a comb with a piece of silk? I’ve also heard that helicopter rotors generate static charge. Is it something to do with the continuous motion?
(We can generate all the power we need…by petting a fifty-foot kitty-cat, or getting Paul Bunyan to shuffle his feet over a nylon carpet!)
I’m searching for the same answer! Every time I get a Wendy’s lemonade (plastic cup and paper straw) it shocks me when I go to put my lips to the straw?!?!
And thank you for bringing one of our dead threads back to life.
I think water probably acquires charge rushing through the nozzle. There are lots of flow situations that transfer charge, from lightning clouds on down.
There’s an interesting high voltage generator made from two metal cups, each coming to a point with a fine hole at the bottom, like funnels except so tight the water just drips. And, each cup has a metal arm reaching over to a ring positioned below and around the outlet of the other cup. Randomly one will have higher potential than the other. As a result, continued dripping keeps concentrating charge on the forming drops, drawn there by the ring connected to the opposite cup. The two cups wind up with big positive and negative voltages.
That’s it! Though I think there are different possible configurations, and the one in this illustration is a little different than what I described. The illustration shows a single water source feeding two droppers, which clearly constrains the droppers to have the same potential, and they get voltage between two receivers. I was describing a version with two insulated water sources, which exhibit the potentials. Still, it’s the same basic idea, in which those rings are what cause charge to concentrate on the droplets as they form.