@badastro Model trains usually run at 12v (at full speed). But you can put your fingers on the tracks, and nothing will happen. A 12v car battery, on the other hand.

@badastro But.... I find that talking about electricity via analogies to other forces, like gravity, or moving fluids in pipes, are helpful a bit, but always break down. Electricity is it's own thing.

@badastro OMG this is awesome, but I have to admit I was one of those using the nonsensical units and I should know better. I'm going to go sit in the corner and sob with my shame now.

@14mission I have held both terminals of a car battery many times. As with the model railway, you don't feel anything. How can it electrocute you?
@badastro

@badastro Since decibels are a measure based on a reference, I propose a dBAU referenced to the AU. Then you could say that the car is about -208 dBAU away.

Excellent write-up.

Maybe you could have added that volts x amperes is power, which is energy per unit time. So a high value of volts x amperes (watts or kilowatts) hitting a person implies that person getting zapped by a large amount of energy in an instant. (I am ignoring nuances of DC/AC current, the basic point still holds.)

We should start talking about getting hit by so many kilowatts of electrical power!

@badastro We had an optics table in the lab that housekeeping kept dusting… and knocking mirrors out of alignment. So we put up a sign that read “Danger! 10,000 Ohms”. Problem solved, except that the lowest-ranking grad student had to dust it.

@badastro "So, the higher the rock is dropped from, the more force it can exert."

Terminal velocity joined the chat.

@greenpete @badastro Ok, read around.
Looks like 12v isn't enough to overcome the resistance of your skin.
If your hands were *really* wet there might be some danger.
If the terminals were close enough to touch both with your tongue as when testing a 9v battery--you wouldn't want to do that!
Well thanks.

@mariejulien Asteroid impacts waiting to reply