Power Irradiance Homework: Find Intensity

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SUMMARY

The discussion centers on calculating the intensity of a wave using the Poynting vector in the context of electromagnetic theory. Participants confirm that the intensity is equivalent to the average value of the Poynting vector, which has units of W·m-2. The relationship between the speed of light (c), permittivity (ε0), and permeability (μ0) is also highlighted, specifically the equation c = 1/√(ε0μ0). The conversation emphasizes the importance of understanding these concepts for solving related physics problems.

PREREQUISITES
  • Understanding of electromagnetic theory
  • Familiarity with the Poynting vector
  • Knowledge of the relationship between permittivity and permeability
  • Basic calculus for averaging functions
NEXT STEPS
  • Study the derivation and applications of the Poynting vector in electromagnetic waves
  • Learn how to calculate the average value of functions in physics
  • Explore the implications of the relationship c = 1/√(ε0μ0) in wave propagation
  • Investigate the significance of intensity in different physical contexts
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone involved in the study of electromagnetic waves and their properties, particularly those focusing on wave intensity calculations.

OhNoYaDidn't
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Homework Statement


30idtmc.jpg
[/B]

Homework Equations



The Attempt at a Solution


I found the expression for the magnetic field, and then the Poynting vector.
2nu6e6u.jpg


If i find the intensity, that's the same as finding the average value of the Poynting vector, and the cos^2 disappears... Can you tell me what to do next?
Thank you.
 
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Bump Bump. Does anyone know what to do next?
 
OhNoYaDidn't said:
Bump Bump. Does anyone know what to do next?
Please observe the Forum Rule regarding bumping.

Bumping
Do not "bump" one of your threads to the top of a forum's thread list by posting a basically empty message to it, until at least 24 hours have passed since the latest post in the thread; and then do it only once per thread.​
 
OhNoYaDidn't said:

Homework Statement


30idtmc.jpg
[/B]

Homework Equations



The Attempt at a Solution


I found the expression for the magnetic field, and then the Poynting vector.
2nu6e6u.jpg


If i find the intensity, that's the same as finding the average value of the Poynting vector, and the cos^2 disappears... Can you tell me what to do next?
Thank you.
What does the Poynting vector tell you about the wave's intensity? What are it's units?

How is the speed of light, c, related to ε0 and μ0 ?
 
I wasn't aware of that rule, thank you for pointing it out.
The intensity is the mean value of the Poynting vector. The units of the Poynting vector are W.m^-2, the same for intensity..
I can use the retation c=1/sqrt(ε0*μ0), and therefore reducing 1/cε0 = sqrt(ε0/μ0). What should i do next?

Thanks for your reply.
 

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