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## Homework Statement

E(x,y,t)=(2i/sqrt(5)) + (j/sqrt(5)) Eo cos( 2pi(1/lamda)[2x/sqrt(5) - y/sqrt(5)]-[ft] )

## Homework Equations

I Know k =2pi/lamda for 1D wave

I know K vetor=k dot r

I know K vector shows the direction of propogation, and must be perpendicular to E and B.

## The Attempt at a Solution

Got 1/3 points on this part of my exam.

Kvector=2pi (1/lamda) [2/sqrt(5) - 1/sqrt(5)] * (2i/sqrt(5)) + (j/sqrt(5))

I know I have to check for normalizaton, and it is normalized.

Obviously this is wrong. I'm not sure how to define k for a multi dimensional wave, and my textbook does not show any example problems for 3 dimensional waves., or shows solutions for any multidimensional waves that involve K.Is the answer simply the resultant vector of kx and ky?

sqrt( (2/sqrt(5))^2 + (1/sqrt(5))^2)) which just equals sqrt(1)=1.

Edit: Referred back to Griffiths electrodynamics, and think I Figured it out.

K vector = K * r = (2pi/lamda) ( 2x^ / sqrt(5) - 1y^ / sqrt(5))

where x^ and y^ indicate the unit vectors xhat and yhat, not x to a power of ____.

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