Respuesta :
I think the correct answer from the choices listed above is the first option. An electromagnet is a temporary magnet because the magnet is only present when a current is present. The magnetic field disappears when the current is turned off. Hope this answers the question. Have a nice day.
Answer:
The magnet is only present when a current is present.
Explanation:
As we know that in electromagnet there is a coil of certain resistance which is connected to a energy source which will provide constant potential difference to the coil
Due to constant potential difference the coil will have a current flow in it due to which there exist a magnetic field along the axis of the coil
this magnetic field is only possible when current is flowing in the coil
So it is given as
[tex]B = \frac{\mu_0 N i}{L}[/tex]
here we know
N = number of turns
L = length of solenoid
i = current in it
So correct answer is
The magnet is only present when a current is present.