Learn how to make a business card stick to a glass in this dinner table magic tricks video from Howcast.
Q: You want to see something cool?
Q: All right, here, watch this. If I put a card on top of there and turn it over what do you think will happen if I let go?
A: It’ll go over.
A: Oh my, gosh! How does it stay?
Q: It stays. You want to know?
Q: All right, this is actually just air pressure. It works all by itself. So what happens is there’s greater air pressure outside the glass than there is inside the glass, and as you learn in science class, air pressure always moves from greater to lesser. So there’s about 14.7 pounds per square inch pushing both this way, this way, this way, this way, so when you let go, the card stays.
A: Let me see.
A: Oh, wow, that’s so neat.
Q: And you can do it best with a full glass of water.
Q: Oh, yeah, a full glass of water and an index card, it’s a great way to learn about science and…
Q: … scare people. And that’s how you turn a glass upside down with just a card.
Q: Cheers. You see more magic that way.