The working principle of a d.c electric bell is that when the switch is pressed , a current flow through the electromagent and a magnetic fleid is produced to attract the hammer.
What i want to ask is that why the hammer can be attracted ? By Lenz Law, it shoud induce a magnetic field to repel when it experience a changing magetic field.
What i want to ask is that why the hammer can be attracted ? By Lenz Law, it shoud induce a magnetic field to repel when it experience a changing magetic field.