Understanding Wave Polarisation: Intensity Changes and Filter Effects Explained

In summary, the intensity of polarized light passing through a filter with a gap at an angle to its initial polarization direction can be calculated using the equation I=I0cos2θi, where I0 is the initial intensity and θi is the angle between the light's initial polarization direction and the axis of the polarizer. The intensity will be reduced as the angle increases between the gap and the light's vibration plane, with no light coming out if the gap is perpendicular to the plane.
  • #1
question dude
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I have two queries:

- if unpolarised light passes through a polaroid filter so that light coming out of the filter becomes polarised, would intensity (brightness) of the light become reduced as a result?

- if you have a polarized wave, and it passes through a filter that has a gap which is at an angle to the plane of this polarized wave's vibrations (but not perpendicular to it), would anything come out of the filter? (just to give an example, say you have a wave vibrating up and down in the vertical plane, I understand that if you have a filter which only has horizontal gaps then nothing will come out of the filter, but what if the gap was at an angle somewhere between vertical and horizontal?)


if I haven't made myself clear, please tell me, I can get hold of the textbook and scan the diagram
 
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  • #2
question dude said:
I have two queries:

- if unpolarised light passes through a polaroid filter so that light coming out of the filter becomes polarised, would intensity (brightness) of the light become reduced as a result?

Yes, the intensity will be reduced.
- if you have a polarized wave, and it passes through a filter that has a gap which is at an angle to the plane of this polarized wave's vibrations (but not perpendicular to it), would anything come out of the filter? (just to give an example, say you have a wave vibrating up and down in the vertical plane, I understand that if you have a filter which only has horizontal gaps then nothing will come out of the filter, but what if the gap was at an angle somewhere between vertical and horizontal?)

The intensity of the light can be found by the following equation.
I=I0cos2θi
Where I0 is the initial intensity of the light before passing through the polarizer and θi is the angle between the light's initial polarization direction and the axis of the polarizer.
 
  • #3
Drakkith said:
Yes, the intensity will be reduced.The intensity of the light can be found by the following equation.
I=I0cos2θi
Where I0 is the initial intensity of the light before passing through the polarizer and θi is the angle between the light's initial polarization direction and the axis of the polarizer.

thank you very much, although I'm not up to that standard yet so I haven't come across it (I'm in high school here), the formula there makes sense, because cos 0 = 1, so the intensity would be exactly the same if the gap is in the exact plane as the wave's vibration, and cos 90 = 0 if the gap is right angle to the plane in which the wave vibrates in
 

FAQ: Understanding Wave Polarisation: Intensity Changes and Filter Effects Explained

What is wave polarisation?

Wave polarisation is the orientation of the electric field of a wave. It describes the direction in which the electric field oscillates as the wave propagates through space.

How does wave polarisation occur?

Wave polarisation occurs when a wave is confined to move in a single plane. This can happen when a wave is reflected off a surface or when it passes through a polarising filter.

What are the different types of wave polarisation?

There are three main types of wave polarisation: linear, circular, and elliptical. Linear polarisation occurs when the electric field oscillates in a single direction, while circular and elliptical polarisation occur when the electric field rotates around a central axis.

What is the significance of wave polarisation in everyday life?

Wave polarisation has many practical applications in everyday life. For example, polarised sunglasses use polarisation to reduce glare from horizontal surfaces, such as water or roads. It is also used in radio and television transmissions to improve signal quality.

Can all types of waves be polarised?

No, not all types of waves can be polarised. Only transverse waves, where the vibrations are perpendicular to the direction of propagation, can be polarised. Longitudinal waves, where the vibrations are parallel to the direction of propagation, cannot be polarised.

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