Electromagnets can easily be turned on and off.
Explanation:
An electromagnet produces magnetic field which is done by the electric current. These electromagnets contain a wire would like a coil. The current passes through the wire and the magnetic field is concentrated in the center which is the "center of the coil".
When the current is "turned off" the magnetic field "disappears". This shows that we have can have a control over the passage of current or the magnetic field. Thus, the "main advantage" of the electromagnet is that it can be easily turned on and off whenever necessary.
I believe the correct answer would be B. Semipermeable means that it allows certain substances to pass through, and certain other ones to not pass through. So given all of your options, I would say that B makes the most sense. Hope this helped!
-TTL
Answer:umm what y need help with ???
Explanation:
