Help! How do I build a strong electromagnet that runs off batteries?

[Quad]

correct me if i'm wrong:

take a long iron nail, use 22-gauge wire and wrap the wire in a tight spiral around the core. I read that the more spirals you have, the stronger the electromagnet is. but how can i wrap the spiral in multiple layers? once i come to the end of the nail...how can i make more spirals? just let the wire travel along the length of the nail and start spiralling again?

and is it the tip of the nail that becomes magnetized? or the entire length of it?
thx in advance!

 

[Kelvrick]

YOu just wrap the wires on top of the other wires.

 

[tikwanleap]

Yep, just wrap the wires on top of the existing wires. One thing to make sure of is to always go clockwise or counterclockwise. If you mix them, then then the magnet won't be as strong because some of the magnetic flux will be cancelling itself...