electromagnetic waves?

Question

A.are compresssional waves
B.are transverse waves
C.must have a medium
D.are generated by static electricity

Answer 1

I shouldn't be doing your homework for you, but I will give you some clues. Try to think about it logically.

If EM waves were "compressional" waves, then what is being compressed? How can light travel across empty space if it needs to compress a medium? This reasoning should eliminate answers A and C.

You should know that answer D cannot be true, since only moving electrical charges (as in an electric current moving through a conductor such as a radio antenna) produce EM waves.

So what answer is left?

===edit===
Technically, lightening is not static electricity, since charge flows (temporarily) from the Earth to the ground. The flow of charge creates EM waves.

Lightening is CAUSED by the build-up of static charge in the clouds, but there are no radio waves produced until the charges flow into a lightening strike (or the movement of charge in a prestrike).

Answer 2

Yes, the above answer is correct. But since lightning, a form of static electricity produces broad band em waves, D is also correct.

Marconi's first radio was nothing more than a spark gap that produced broad band em waves.