# What do polarisation lens block?

• TT0
In summary: A horizontally orientated polarising filter blocks light in which the electric field is oscillating in the horizontal plane and the magnetic field is oscillating in the vertical plane but not light in which the electric field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane.
TT0
Electromagnetic waves are created by a accelerating charge that induces a changing electric field, that induces a changing magnetic field which propagates together through space. The electric and magnetic field are at right angles to each other. Polarisation blocks all but one plane of the transverse wave. Does it block the electric or magnetic field? Or is the transverse wave of light caused by the wave nature of the direction the propagation of the 2 fields (so it is perpendicular to both electric and magnetic fields at all times)? Or am I misunderstanding something?

Thanks

TT0 said:
Does it block the electric or magnetic field?

when we talk about light and its polarisation, we are always referring to the electric field
So, for example, your polarising sunglasses block the electric field that doesn't align with the
polarity of the polarising filter

TT0 said:
Does it block the electric or magnetic field?
Both. A vertically oriented polarizing filter blocks light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane.

TT0
The first sentence in #1 should stop earlier and read:

"Electromagnetic waves are created by a accelerating charge that induces a changing electromagnetic field."

The causal and local sources of the electromagnetic field (there is not an electric and a magnetic field but only electric and magnetic components of the electromagnetic field, depending on the frame of reference they refer to) is the charge-current distribution, as is clearly shown by the Jefimenko equations:

https://en.wikipedia.org/wiki/Jefimenko's_equations

TT0
Nugatory said:
Both. A vertically oriented polarizing filter blocks light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane.

I see, just to check my understanding, does that mean a horizontally orientated polarising filter blocks light in which the electrical field is oscillating in the horizontal plane and the magnetic field is oscillating in the vertical plane but not light in which the electrical field is oscillating in the vertical plane and the magnetic field is oscillating in the horizontal plane?

Thanks a lot

## 1. What is polarisation and why is it important?

Polarisation refers to the direction of light waves as they travel. It is important because it affects how light is reflected, scattered, and absorbed by different surfaces, which can impact our vision and cause glare or distortion.

## 2. How do polarisation lenses work?

Polarisation lenses have a special filter that only allows light waves to pass through in a specific direction, while blocking out waves that are oriented in other directions. This helps to reduce glare and improve overall visual clarity.

## 3. What types of light do polarisation lenses block?

Polarisation lenses primarily block horizontally polarised light, which is usually the type of light that causes glare from reflective surfaces such as water or snow. They can also block some UV light, which is important for protecting our eyes from harmful rays.

## 4. Can polarisation lenses improve vision for people with certain eye conditions?

Yes, polarisation lenses can be beneficial for people with certain eye conditions such as cataracts, as they can reduce glare and improve overall visual comfort. However, it is always best to consult with an eye care professional for personalized recommendations.

## 5. Are polarisation lenses necessary for everyday use?

No, polarisation lenses are not necessary for everyday use. They are most commonly used for outdoor activities or in situations where glare is a concern, such as driving, fishing, or skiing. However, some people may find them beneficial for everyday wear if they are frequently exposed to bright sunlight or glare.

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