the electromagnet is characterized by what

the electromagnet is characterized by what
Electromagnet has many advantages: you can use the presence or absence of magnetic solenoid off through current control; magnetic size can use the current strength or coil turns to control; also change the resistor to control the size of magnetic control current drum separator size; it The pole can be controlled to change the direction of the current, and so on. Namely: the strength of the magnetic can be changed to control the presence or absence of magnetism, the magnetic pole direction can be changed, the current may be due to the disappearance of the magnetic disappear.