Instructions: Select the correct answer. 
An electromagnet is a device in which moving electric charges (current) in a coil of wire create a magnet. 
What’s one advantage of using electromagnets in devices? 
A. Electromagnets have a strong, constant magnetic field. 
B. Electromagnets are more powerful than permanent magnets. 
C. Electromagnets don’t need a source of electricity to work. 
D. Electromagnets can easily be turned on and off.