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电磁铁指的是内部带有铁芯、利用电流的磁效应而获得磁性的装置,铁芯要用既容易磁化,又容易消失磁性的软磁性材料制做.电磁铁相对于永磁铁有许多优点:电磁铁磁性的有无可以用通、断电流控制,磁性的大小可以用电流的强弱或线圈的匝数来控制,电磁铁极性的改变可以通过改变电流的方向来实现等.正因为电磁铁拥有这么多的优点,所以它在日常生活中有着极其广泛的应用,例如电磁起重机、电铃、电路自动限流器、电磁继电器等,也因而成为考试的重点命题对象之一.
An electromagnet is a device that has an iron core inside and uses the magnetic effect of the current to obtain the magnetic property, and the iron core is made of a soft magnetic material that is easy to magnetize and can easily disappear. There are many advantages of the electromagnet with respect to the permanent magnet : Whether or not the electromagnet magnet can be controlled by on and off current, the size of the magnet can be controlled by the strength of the current or the number of turns of the coil, the change of the electromagnet polarity can be achieved by changing the direction of the current, etc. Because of Electromagnet has so many advantages, so it has a very wide range of applications in daily life, such as electromagnetic cranes, bells, automatic circuit limiter, electromagnetic relays, etc., has therefore become one of the key subjects of the exam.