What Are the Units of Electromagnetic Wave B?

AI Thread Summary
The discussion focuses on deriving the units for the magnetic field B in electromagnetic waves using the equation B = k / w (Z x E). Key points include the definitions of variables such as k (wave number), w (angular frequency), and E (electric field), with discussions on their respective units. The participants clarify that B can be expressed in terms of velocity, leading to the conclusion that B has units of [A] (amperes). There is a caution about the distinction between voltage (V) and velocity (v) due to potential confusion in notation. Overall, the derivation emphasizes the importance of unit consistency in electromagnetic wave equations.
dowjonez
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B = k / w ( Z x E)

Check this equation by deriving the units for B


w = omega
Z = z hat
 
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What have you done so far?
 
k = 2pi / lamdba
w = 2 pi V / lamba

So B = 1/V ( Z X E)

B = 1/ [ m / s ] ( Z X E )

[E] = [q] / [E0] [ R^2]

[E] = [C] / [C^2/ Nm^2] [ m^2] = [N / C]

B = [s / m] * ( Z x [N / C])
 
but = N / A * m
 
[C / s] = [A], so 1/[A] = [s / C]

[N] / [Am] = [N / m]*[1/A], right? so [N]/[Am] = [s/C]*[N/m], or [s/m]*[N/C]

I may have missed something, but I don't see a problem.

Also, be careful. V = voltage, v = velocity. It was hard to read your posts with some of those things in caps. This could have been easier if you noticed immediately that k/w = 1/v, which has units [s/m], and that E always has units [N/C]. Maybe you were expected to work it all out, but that's silly.
 
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