SOmeone heLp me in physics....:(?

Question

can someone help me solve this?

1. the energy S carried by electromagnetic waves in space is proportional to the product of two vectors E and B, where E and B represent the instantaneous values of the electric and magnetic fields. in this case the energy S is a vector, its direction being that in which the energy is flowing. must we take the dot or the cross product of E and B in order to find S?

a. the dot product

b. the cross product

c. the info given is not sufficient to determine which product is required.

thanks! 10 points for the best answer.

Answer 1

I'm not to sure, but i think you would have to take the cross product...the electric and magnetic energy densities are equal in e-m waves.

ya i'm unsure abt it...sorry!

Answer 2

it has to be the croos or the vector product bcoz s which is the resultant is itself a vector which can not be possible if we take the dot product. so definitely its the cross product no need to look anywhere else the answer is in your question (s is a VECTOR)