Malus Law Calculator

What is Malus's Law?

Malus's Law describes how the intensity of polarized light passing through a polarizer changes with the angle between the light's polarization direction and the polarizer's axis. It states that the intensity of the transmitted light is proportional to the square of the cosine of the angle θ between the light's polarization direction and the polarizer's axis.

How to use this calculator

1. Enter the initial light intensity (I₀) in W/m²
2. Enter the angle θ between the light's polarization direction and the polarizer's axis in degrees
3. Click the "Calculate" button to compute the final light intensity
4. The result will be displayed in the Final Light Intensity field

Working Principle

When unpolarized light passes through a polarizer, it becomes polarized along the polarizer's axis. If this polarized light then passes through a second polarizer, the intensity of the transmitted light depends on the angle between the two polarizers according to Malus's Law:

I = I₀ × cos²(θ)

Where:

• I = Final light intensity
• I₀ = Initial light intensity
• θ = Angle between the polarization directions of the two polarizers

Applications

Malus's Law has numerous applications including:

• Optical instruments like polarizing filters in photography
• LCD displays
• Glare reduction in sunglasses
• Quantum mechanics experiments