Electromagnetic wave, intensity, electric field problem

AI Thread Summary
The discussion centers on calculating the root mean square (rms) value of the electric field from a proposed electromagnetic wave transmission of 850 kV and 1100 A over an area of 80 m². Participants share relevant equations, including the Poynting vector and power formulas, while attempting to derive the correct values. Several incorrect attempts at the electric field value are noted, with one participant suggesting the need to convert kV to V for accurate calculations. The conversation emphasizes the importance of using the correct units and formulas to find the average magnitude of the Poynting vector. Ultimately, the focus remains on solving for the rms electric field in kV/m.
ashleyd
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Homework Statement


Instead of sending power by a 850 kV, 1100 A transmission line, one desires to beam this energy via an electromagnetic wave. The beam has uniform intensity within a cross-sectional area of 80 m2. The speed of light is 3×10^8 m/s and the permeability of free space is 4×10^-7 T · m/A.
Find the rms value of the electric field.
Answer in units of kV/m

Homework Equations


P=IV
poynting vector = S = EB/mu0
Not sure if the following equations are relevant:
Power = I/Area
S=(E^2)/mu0*c

The Attempt at a Solution


I have tried using the formulas above, along with changing the kv to v
the answers i have gotten through this that are incorrect include:
18774.62904
593705.9
2099.06734
66378.33756
 
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<S> = \frac{E_o^2}{2 \mu_0 c}

Where <S> is the time averaged magnitude of the Poynting vector for a plane wave.

What value did you calculate for <S>?
 
The value I got for S, without converting kV to V was 11687.5
 
Okay, convert to watts/m2 and use the given formula to solve for Eo.
 

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