(2012?Suqian) as shown in the figure, after the switch S is closed, the following statements are correct ( ) A. The upper end of the electromagnet A is the N pole B. The spring has elastic potential energy C
(1) by the question in the figure can be seen: when the switch is open, no current in the circuit, the light is on, the electromagnet is not magnetic, the spring plate pulls the armature up, the spring has elastic potential energy; motor circuit is disconnected; lamp work; when the switch is closed, the electromagnet circuit will be on, the light is off, the electromagnet has a magnetism, the armature will be in the role of electromagnetic attraction to turn on the motor circuit.
(2) According to Ampere's rule, the upper end of the electromagnet is the S pole.
The choice is B.