Is Malus' Law a law, or does it derive from Maxwells equations?

In summary, Malus' law is a quantum law that can be derived using both classical and quantum methods. It naturally falls out of Jones Calculus, which involves representing an EM wave as a vector and using matrices to transform it. This theory is based on Maxwell's equations, making it a fundamental part of electromagnetic wave theory. There are various ways to calculate Malus' law, including a classical derivation by Brukner and a quantum derivation by using imaginary numbers.
  • #1
Tez
50
0
Well the question is in the title. Does Malus' Law (http://en.wikipedia.org/wiki/Malus's_law ) follow automatically from Maxwell's equations, or is it really an extra thing put in by hand? In particular I'm interested if there is a purely classical electromagnetic explanation (i.e. without having to go into the quantum mechanics of wither the light or the polarising medium at all...)
 
Physics news on Phys.org
  • #2
Malus' law falls naturally out of Jones Calculus.

http://en.wikipedia.org/wiki/Jones_calculus

Jones Calculus basically involves representing an EM wave as a vector, and optical components as matrices, with the matrices defined such that it transforms the incoming EM wave vector in the correct way. For example, a half-wave plate will have a matrix that rotates the incoming vector by 90 degrees.

Jones Calculus falls naturally from the theory of EM-waves, which in turn drops out of Maxwell's equations.

Claude.
 
  • #3
Malus law is a quantum law, in principle. Can we calculate it in a quantum way, so for photons? In the above link this not exist.
This was calculated by Brukner, but without imaginary numbers. I am interested in classical derivation?
quant-ph/0212084v1
 
  • #5


Malus' Law is a fundamental principle in the study of optics and can be derived from Maxwell's equations. It is not an extra thing put in by hand, but rather a direct consequence of the behavior of electromagnetic waves. In particular, Malus' Law can be derived from the wave theory of light, which is a classical electromagnetic explanation.

Maxwell's equations describe the behavior of electromagnetic waves, including light. They show that light is a transverse wave, meaning that the electric and magnetic fields oscillate perpendicular to the direction of propagation. This oscillation can be thought of as a wave with a specific orientation, known as polarization.

Malus' Law states that the intensity of light passing through a polarizing medium is directly proportional to the square of the cosine of the angle between the polarization direction of the incident light and the transmission axis of the polarizer. This means that as the angle between the two directions increases, the intensity of the transmitted light decreases.

This behavior can be explained by considering the interaction between the incident light and the polarizing medium. The polarizing medium acts as a filter, allowing only light with a particular polarization direction to pass through. As the angle between the incident light and the transmission axis of the polarizer increases, the component of the electric field that is parallel to the transmission axis decreases, resulting in a decrease in the intensity of the transmitted light.

In conclusion, Malus' Law is a fundamental principle in optics that can be derived from Maxwell's equations. It is a classical electromagnetic explanation that does not require the use of quantum mechanics.
 

1. What is Malus' Law?

Malus' Law is a fundamental principle in optics that describes how light is transmitted through polarizing filters. It states that the intensity of polarized light passing through a polarizer is directly proportional to the cosine squared of the angle between the polarizer's transmission axis and the direction of the incident light.

2. Is Malus' Law a law or a derived equation?

Malus' Law is considered a law in optics, meaning that it is a fundamental and universally applicable principle. It is not derived from other equations, but rather is based on experimental observations and mathematical calculations.

3. How does Malus' Law relate to Maxwell's equations?

Maxwell's equations describe the fundamental laws of electromagnetism, including the behavior of light. Malus' Law is not derived from Maxwell's equations, but it is consistent with them and can be used to predict the behavior of polarized light in accordance with electromagnetic theory.

4. Are there any limitations to Malus' Law?

Malus' Law assumes that the polarizing filter is ideal and that the incident light is monochromatic (single wavelength). In reality, polarizers have imperfections and light is composed of multiple wavelengths, so there may be some deviation from the predicted behavior.

5. How is Malus' Law used in scientific research?

Malus' Law is used in a variety of scientific fields, including optics, astronomy, and atmospheric science. It is a fundamental principle that is used to understand and predict the behavior of polarized light in various experimental and natural settings. It is also used in the development of technologies such as polarized sunglasses and LCD displays.

Similar threads

Replies
7
Views
1K
  • Electromagnetism
Replies
7
Views
3K
Replies
3
Views
759
Replies
11
Views
2K
Replies
0
Views
848
  • Electromagnetism
Replies
4
Views
1K
Replies
6
Views
1K
Replies
10
Views
1K
Replies
3
Views
2K
Replies
3
Views
1K
Back
Top