Principle of spring lock for medical equipment

(1) According to Ampere's rule, it can be judged that the thumb points to the right, that is, the right side is the N pole, so the left side is the S pole. If different magnetic poles attract each other, electromagnets and bar magnets will attract each other.

(2) In order to work normally, that is, to maintain the magnetism of the door, but the magnetism can disappear after power failure, so we choose iron; To increase magnetism, we can increase current, that is, increase voltage, or increase the number of coils, so that magnetism can be very strong.

So the answer is: (1)S, attracting, (2)B, increasing the voltage or increasing the number of coils.