How does potassium-argon dating work?

Question

How does it differ from radiocarbon dating?

Answer 1

Potassium is also a radioactive substance....that's right, bananas and broccoli are radioactive! K-Ar dating works in much the same way as carbon dating. A substance containing potassium will have a certain number of radioactive isotopes by weight. How many isotopes are left, eg. how radioactive it is, determines the sample's age based on existing data for the K half-life.

It's different from carbon dating because carbon and potassium are two different elements. I believe the potassium half-life is longer.