formula needed

[Raoul Raffagli]

Hi all. Planning a new project that includes also mechanical parts
electrically driven. I need to calculate what kind of electro-magnet I must
use and what current does it need to attract a metallic plate at a certain
distance with a determinate force. I can calculate how many Newtons I need,
but i cannot decide how to build the electro-magnet and the power needed.
Looking for a formula, also to see the gain in newton changing the power
applied. Any physician out there that can help? Many thanks,
    Raoul, from Italy

PS: I'm sorry for my poor english, but i'm very poor in tecnic language. I
promise I'll study it when I've got time.