Puzzles and brainteasers

I have two coins which add together to make twelve pence, one of the coins isn't a two pence piece. what are the two coins?

Imagine you are in a room with 3 switches. In an adjacent room there are 3 bulbs (all are off at the moment), each switch belongs to one bulb. It is impossible to see from one room to another. How can you find out which switch belongs to which bulb, if you may enter the room with the bulbs only once?

A table tennis ball fell into a tight deep pipe. The pipe was only a bit wider then the ball, so you can not use your hand. How would you take it out, with no damage?

How can you throw a ball as hard as you can and have it come back to you, even if it doesn't hit anything, there is nothing attached to it, and no one else catches or throws it?


For more brain teasers like these go to:

http://hlavolamy.szm.sk/brainteasers/puzzles-riddles.htm