In cars, it governs air flow to the carburetor; in a shotgun, it controls the amount of spread of the shot
- Explain that Stuff [PAR] Sep 23, 2016 ... Cars, trucks, and buses turn fuel into power by mixing it with air and ... engines 
are designed to take in exactly the right amount of air so the ... At the top, there's a 
valve called the choke that regulates how much air can flow in.