Question

which of the following decrease the strength of an electromagnet?

Answer 1

what are the 'following' choices?

Answer 2

when distance increases, electromagnetic forces should decrease.

Answer 3

Probably true, but there's nowhere near enough information in the question. Lowering the current, lowering the number of turns, would decrease the strength of an electromagnet.

Answer 4

1) When distance increases the strength of electromagnet decreases.
2) when temperature increases the strength of the electromagnet decreases as well
3) Using an electromagnet again and again its strength decreases