18. Which one of the following is not a part of an electromagnet?

A.the coiled wire
B. the nail as the core
C. the pins attracted by the electromagnet
D. the dry cell as the source of electricity

19. Which of the following devices makes use of electromagnets?

A. telephone
C. electric bell
B. electric buzzer
D. all of the given responses

20. What happens when a part of an electromagnet is disconnected?

A. It loses its magnetism.
B. Electricity continues to flow through it.
C. The electromagnet becomes a permanent magnet.
D. There is an increase in the number of materials attracted.​