I'm trying to decide it something that happened recently was lucky or unlucky. Here's the story:
My folks and I were on our way back home from school when we decided to stop off at the grocery store. Mum and I stayed in the car while Dad went in to pick up food preparation stuffs. He got back and tried to start the car and... nothing. The battery had died. The good news is that there was a mechanic/garage thingy right across the parking lot.
|As the crow said, "Car! Car!" (A little Mainer humor for y'all)|
<PHYSICS TIME> So a car need the battery to get it going, right? The batter starts the car's motor. A motor, of course, is a device that uses a magnetic field to convert electrical energy (current) to kinetic energy (movement). A wire coil is connected to a source of change in voltage (the battery), meaning it gets current flowing through it. If the wire coil is in a magnetic field, it will start to move. Neat! Now the car's wheels can start turning!
BUT WAIT, THERE'S MORE! Anything that conducts current gets a magnetic field OF ITS VERY OWN. That means the spinning coil is now an electromagnet, and what's more, it's spinning! We all know that it's possible to induce voltage (and thus current) if there's a wire loop and a changing magnetic field, and with the spinning coil, there's a constantly changing one! That means that as the car (remember the car?) drives and the motor works, it can also recharge its own battery! Nice. </PHYSICS TIME>
Mum and I were listening to the radio with the motor off. Yes, that's right, we ran down the battery. It was still strange because we were only in the car for about twenty minutes. Our car battery was faulty or something. BUT if we had been running the air conditioner while we listened to the radio and rolled the windows up and down for an hour (or something), there wouldn't have been anything strange about the battery dying.
(PS: Okay, guys. What's the verdict? Unlucky that the battery died, or lucky that the car busted less than a street away from a mechanic?)