Question

An electromagnet can be made by wrapping wire around which object?

A. Plastic pipe

B. Plastic knife

C. Wooden sticks

D. Metal rod

I think its D..?

Answer 1

a core of ferromagnetic metal will increase the magnetic field, and then make the lectromagnet useful, if you use, for example, plastic or wood, you will still get a magnetic field, but too weak.
so i think D is the best answer here

Answer 2

Ah ok, that makes a little sense XD thanks!