Irradiance and electric field strength

In summary, the conversation discusses the issue of converting electric field strength from V/m to W/cm^2 in a QM code. The solution is to solve an integral using the duration time of the pulse, electric field strength, permittivity of vacuum, and length of the simulation box. The result can then be divided by the area of the side perpendicular to the axis to obtain the power of the field in W/m^2. The conversation ends with the poster sharing their solution for others who may encounter the same problem.
  • #1
nadlerchen
2
0
Dear physicists,
I am desperate. I am using a QM code to propagate a wavefunction of a system that experienced an electric field pulse. However, in literature all values for the electric field strength are given in V/m but the program asks for W/cm^2! I am kind of very confused here and did not find any answer that might relief me from confusion... Does anyone know how this can be done?
 
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  • #2
Well, finally with the help of my flatmate I figured it out. I post it just in case anybody else like me has this problem...
One has to solve the integral

[tex]\frac{1}{\Delta T} \int \frac{1}{2} \epsilon_{0} |E|^{2} d^{3}r[/tex]

[tex]\Delta T[/tex] is the duration time of the pulse, E the electric field strength in V/m and [tex]\epsilon_{0}[/tex] is the permittivity of vacuum. r is the length of the simulation box where the molecule is located in. This gives me the power of the field in W. Finally, divide this by the area of the side perpendicular to the axis along which the pulse enters the simulation box and W/m^2 results.
 

1. What is irradiance and how is it related to electric field strength?

Irradiance is a measure of the amount of electromagnetic radiation (such as light) that is incident on a surface per unit area. It is directly related to the electric field strength, as the electric field is responsible for the propagation of electromagnetic radiation. A higher electric field strength will result in a higher irradiance value.

2. How is irradiance and electric field strength measured?

Irradiance is measured in units of watts per square meter (W/m^2), while electric field strength is measured in volts per meter (V/m). These measurements can be taken using specialized instruments such as radiometers and electric field probes.

3. What is the difference between irradiance and radiant flux?

Irradiance and radiant flux are often used interchangeably, but there is a subtle difference between the two. Irradiance refers to the amount of radiation incident on a surface, while radiant flux refers to the total amount of radiation emitted from a source in all directions.

4. How does distance affect irradiance and electric field strength?

As electromagnetic radiation travels through space, it becomes more spread out and therefore the irradiance decreases with distance. This is known as the inverse square law. Similarly, the electric field strength also decreases with distance according to the inverse square law.

5. What are some applications of measuring irradiance and electric field strength?

Measuring irradiance and electric field strength is important in a variety of fields, including telecommunications, environmental monitoring, and medical imaging. It allows us to understand and control the propagation of electromagnetic radiation and how it interacts with different materials and environments.

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