Question

Which of these act perpendicular to each other to produce an electromagnetic wave?

changing crests and troughs

changing electric and magnetic fields

changing compression and energy transfer

changing longitudinal and transverse waves

Answer 1

Well, you need to know about the basics of electromagnetic waves! Or, you can try to put words together from the answers and see which smash-up looks like "electromagnetic."

Answer 2

Hello again, SmileyMan :)

Answer 3

#2. An interesting phenomenon dependent on this relationship is 'induction': http://en.wikipedia.org/wiki/Electromagnetic_induction

Answer 4

@theEric Hello! :)

Answer 5

:)

Answer 6

That's not what I would imagine appropriate.... And I agree with SmileyMan's response. #2.

Answer 7

thanks @smileyman