(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A plane monochromatic electromagnetic wave with wavelength λ = 2.2 cm, propagates through a vacuum. Its magnetic field is described by

[itex]\vec{B}[/itex] = (Bx[itex]\vec{i}[/itex] + By[itex]\vec{j}[/itex])cos(kz+ωt)

where Bx = 1.8E-6 T and By = 3.8E-6 T, and i-hat and j-hat are the unit vectors in the +x and +y directions, respectively.

What is I, the intensity of this wave?

2. Relevant equations

I = P/A = (1/2)cεoE^2

k = (2π)/λ

ω = ck

Bo*c = Eo

3. The attempt at a solution

I found frequency to be c/λ = 13.63GHz.

I have tried setting t to zero in the given equation and plugging in k and ω to find B, then multiplying that by the speed of light to find E.

I then plugged that into I = (1/2)cεoE^2, but that gave me the wrong answer.

I've also tried adding to the two vectors and assumed that equaled Bo (which I don't think it does), and used Bo = (√2ZoI)/c where Zo = 377 ohms.

I've tried <B^2> = (Bo^2)/2 as well.

Is there an important equation I'm missing?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Intensity of Electromagnetic Waves

Can you offer guidance or do you also need help?

Draft saved
Draft deleted

**Physics Forums | Science Articles, Homework Help, Discussion**