# Power Irradiance Homework: Find Intensity

In summary, the conversation discusses the calculation of the intensity and Poynting vector in relation to finding the magnetic field expression and the speed of light. The Poynting vector represents the wave's intensity with units of W.m^-2. The speed of light, c, is related to ε0 and μ0 through the equation c=1/sqrt(ε0*μ0). The next step would be to use the relation 1/cε0 = sqrt(ε0/μ0).

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## The Attempt at a Solution

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

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.

Bump Bump. Does anyone know what to do next?

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.​

[/B]

## The Attempt at a Solution

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

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?

## What is power irradiance and why is it important?

Power irradiance is the amount of power per unit area that is received from an electromagnetic wave. It is important because it helps us understand the intensity of the radiation and its effects on different materials and systems.

## How is power irradiance measured?

Power irradiance is usually measured in watts per square meter (W/m²) or milliwatts per square centimeter (mW/cm²). This can be done using specialized equipment such as a radiometer or photometer.

## What factors can affect power irradiance?

Power irradiance can be affected by a variety of factors, including the distance from the source, the angle of incidence, and the properties of the medium through which the radiation passes. Other factors such as atmospheric conditions and the wavelength of the radiation can also play a role.

## How is power irradiance related to intensity?

Intensity is a measure of the strength or concentration of any type of energy, including electromagnetic radiation. Power irradiance is directly related to intensity, as it represents the amount of power per unit area of a given radiation. The higher the power irradiance, the greater the intensity of the radiation.

## What are some practical applications of power irradiance?

Power irradiance has many practical applications, including in the fields of optics, solar energy, and medical imaging. It is also used in industries such as agriculture, where it can help determine optimal conditions for plant growth, and in manufacturing, where it can be used to control the intensity of laser beams for cutting and welding.

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