WAEC - Physics (2003 - No. 38)
Which of the following statements about an electromagnet is not correct?
it is a temporary magnet
its strength depends on the current
its stength depends on the number of turns in its coil
it has permanent poles
Giải thích
properties of an electromagnet include, 1) its strength depends on current and the number of turns in the coil,2) it is temporary, 3)it does not have permanent poles, and 4) its direction of flow is determined by the direction of current flowing through the coil.