Malus's law

Definition

Malus's law describes the intensity of polarized light after passing through a polarizer. It states that the intensity of the transmitted light is proportional to the square of the cosine of the angle between the polarization axis of the polarizer and the polarization direction of the incident light.

5 Must Know Facts For Your Next Test

1. Malus's law describes the relationship between the intensity of polarized light and the angle between the polarization axis of the polarizer and the polarization direction of the incident light.
2. The intensity of the transmitted light is proportional to the square of the cosine of the angle between the polarization axis of the polarizer and the polarization direction of the incident light.
3. Malus's law is derived from the wave nature of light and the interaction between the electric field of the light and the polarizer.
4. Malus's law is important in understanding the behavior of polarized light and its applications in various fields, such as optics, photography, and liquid crystal displays (LCDs).
5. Malus's law can be used to measure the degree of polarization of light and the orientation of the polarization axis of a polarizer.

Review Questions

• Explain how Malus's law describes the intensity of polarized light after passing through a polarizer.
  • $I = I_0 \cos^2 \theta$, where $I$ is the intensity of the transmitted light, $I_0$ is the intensity of the incident light, and $\theta$ is the angle between the polarization axis of the polarizer and the polarization direction of the incident light. This relationship demonstrates that the intensity of the transmitted light is proportional to the square of the cosine of the angle between the polarization directions.
• Describe the physical principles underlying Malus's law and how it relates to the wave nature of light.
  • Malus's law is derived from the wave nature of light and the interaction between the electric field of the light and the polarizer. When unpolarized light passes through a polarizer, the polarizer selectively absorbs or reflects light waves of certain polarizations, allowing only the light waves with a specific polarization to be transmitted. The intensity of the transmitted light is then determined by the angle between the polarization axis of the polarizer and the polarization direction of the incident light, as described by Malus's law.
• Analyze the practical applications of Malus's law in various fields, such as optics, photography, and liquid crystal displays (LCDs).
  • Malus's law is crucial in understanding the behavior of polarized light and has numerous applications. In optics, Malus's law is used to measure the degree of polarization of light and the orientation of the polarization axis of a polarizer. In photography, polarizers are used to reduce glare and enhance contrast in images. In liquid crystal displays (LCDs), Malus's law governs the operation of the liquid crystal cells, which control the polarization of light to produce the desired image. Understanding Malus's law is essential for the design and optimization of these technologies that rely on the manipulation of polarized light.

Related terms

Polarization:

The property of electromagnetic radiation where the electric field oscillates in a particular direction perpendicular to the direction of propagation.

Polarizer: A device that converts unpolarized light into polarized light by selectively absorbing or reflecting light waves of certain polarizations.

Intensity: The amount of energy passing through a unit area per unit time, which is a measure of the brightness or power of electromagnetic radiation.