# Homework Help: Polarization of Waves

1. Dec 31, 2008

### Billy246

1. Info

Basically, I'm having trouble with this question and it's constituent parts.

http://img181.imageshack.us/img181/6986/question8tn5.jpg [Broken]

2. Relevant equations

No equations for first two parts, it's the visualising that i'm finding tricky.
Part 3 will require some sort of angular velocity equation, yet i'm still unsure.

3. The attempt at a solution

Question part i) Answered (c) horizontally north-south. This seems the logical answer as it is perpendicular to the wave motion.

Question part ii) Shot in the dark would lead me to answer a.

Question part iii) Got lost in the calculation and cannot be sure of calculated answer. I guessed the answer to be answer c - 58 x 10^9

Any help would be greatly appreciated if any is given. Thank you.

Kind Regards,

Billy
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: May 3, 2017
2. Dec 31, 2008

### Niles

(i): When an EM-wave is said to be polarized, the convention is that you are talking about the polarization of the E-field. So in this question, we are told that a plane EM-wave is moving towards right, and the plane of polarization is vertical. So I would say (a).

(ii): The B-field always oscillates in such a way to be orthogonal to the E-field. From (i) I would say (c).

(iii): From the equation for E you see that the magnitude of the wave number k is 260 m^{-1}. Since the wave is travelling in air, we will say the velocity is c. Then we have:

$$k=\frac{\omega}{c} \Leftrightarrow \omega = kc.$$

Thus we get (d).

Have a happy New Year

3. Dec 31, 2008

### Billy246

Thank You Niles,

Much appreciated. Hope the New year treats you well!

Regards,
Billy