Cell Phone Circuitry

The Puzzler

TOM: So that's the question.

RAY: And this is the correct answer. I was there and I witnessed it. Well, the first thing I had to do was to verify that her phone worked, because in order for my theory to be correct, the phone has to be working, because if the phone's dead, the theory doesn't work. So, in fact, by using her phone, I verified that her battery was not dead. Now, I need to give you a little lesson in electricity.

TOM: Go ahead, man.

RAY: When you plug something into your cigarette lighter like your hair dryer, or your portable yogurt maker, electrons that are in your car's battery stream out of that thing, go through the fuse, and go through the wires, and into the socket of your cigarette lighter. They operate whatever it is that you're operating. And everyone understands that principle.

TOM: Sure.

RAY: But when you plug in something that needs to be charged like the cell phone, something interesting is happening, because there are electrons in the cell phone. How do I know that? The battery isn't dead. And when you plug something in that needs to be charged, the reason it does get charged is there's a difference in electrical potential between the car's battery, which is 12 volts, and your cell phone, which is like eight, or nine, or 10 volts, or something like that. So, when you plug the cell phone into the cigarette lighter socket, electrons from your cell phone try to go into the wires in the opposite direction than those electrons from the battery are going.

RAY: So you get the scenario here?

TOM: I've got it, man.

RAY: Electrons are coming from your car's battery. The electrons from the cell phone are trying to escape, but something is wrong here, because things that aren't supposed to be working are working.

TOM: Yeah, I've got it. So your theory is that the electrons from the cell phone are going to light up the lights?

RAY: Exactly.

TOM: How's that happen?

RAY: When there were no electrons coming from the car's battery to the cigarette lighter, those nine volts of electrons in the cell phone, they are emboldened and they will travel wires that they were never intended to travel on and they will actually go to things and energize things like those lights on the dashboard that ain't supposed to be getting energized.

TOM: Wow, how bold. So lights will light up.

RAY: So what I told Manny when I called him on the phone was replace the fuse. She needed a fuse for the cigarette lighter. Anyway, do we have a winner?

TOM: The winner is Andy Gladish from Anacordes, Washington.

[ Car Talk Puzzler ]

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