I just used a bit of stiff wire that held the sensor then bent the wire a bit so the angle was right and it started reading the surface.
Does that mean i got 2 keep tweaking it for different liquids as well???So every liquid got to be held at a fixed angle at which it works?????
In fact, with a little design and use of a slit, you could probably use your detector to measure refractive index
lol very funny....Then, tell the examiners it is just water and prove it by drinking it.
[url said:https://www.uwgb.edu/dutchs/PETROLGY/GENLIGHT.HTM][/url]
Light reflected from non-metallic surfaces is polarized (bottom). The incident light causes electrons in the material to vibrate. Vibrations parallel to the surface emit radiation. Vibrations perpendicular to the surface have a large component in the direction of the reflected light and emit much less radiation. There is one angle where reflected light is 100 percent polarized, but it's not 45 degrees. It depends on the index of refraction of the material but is typically about 30 degrees.
Wed 21st OCT Second Interim Report and Presentation.
Thu 22nd OCT DP refusals posted on the Departmental notice board.
Well not with the latest code for the detector. I did most of the testing with a glass container....Have you tried making the bottom of the container CLEAR??
Yeah, the bottom is usually 27-37 cm from the sensorI think you might be using the 10-80cm sensor with the bottom of the container much closer than 80cm....
Mark Severn asked the Naked Scientists:
Hi All
Love the show and listen to it every week via podcast.
I have a question about polarising sunglasses. I am a keen fisherman and use polarising sunglasses to help me see into the water and spot fish. I understand that they work because the light reflected off the water is polarised horizontally. The sunglasses block this horizontally polarised light. The same effect can be seen with the windscreen of a car and when viewed with polarising lenses it makes it possible to see an oncoming drivers face more clearly.
So why can I still see a reflected image in a mirror? If all reflected waves are horizontally polarised, that is parallel to the reflected surface, should not the light be blocked by the sunglasses as well?
Water is, essentially, an insulator. Light is reflected at an air / water interface due to the change in refractive index. The amount of reflection for normal and parallel polarisation is different (particluarly at oblique angles) which is why polaroid glasses work. You've already lost one polarisation component (50% ) before the glasses get in the way -they just get rid of the other component.
The reflection in a mirror is due to the metal silvering having very high conductivity. Reflection of all polarisations at a highly conducting surface is the same , giving you almost 100% reflection.
Not all reflected waves are horizontally polarised, but only those reflected in an almost horizontal plane. When light from the sun is reflected off a windscreen or a water surface, it is polarized with the same plane of that surface; if you have, instead, a mirror or another reflecting surface near the road, for example, which is put in vertical and a source of light which doesn't come from above but from the road, then light is polarized vertically and you would see the reflection completelly; but you understand that such a situation is very unusual, you should have, for example, lights from a car's lamps reflected off a window (during the night) or something of that kind.
Anyway, remember that even if the surfaces are horizontal, reflected light is not completely polarized; this would happen only at a specific reflection angle: "Brewster's angle", which, for glass is about 56°:
Brewster's angle - Wikipedia, the free encyclopedia
Hi Lightarrow
Are you saying that the only light reflected from a transparent surface is likely to be polarised in the same plane as the surface, and any other polarisations are likely to pass through the surface or be absorbed? Where as a Mirrored surface will reflect all polarisations? I did check the Wiki entry but don't quite understand what is going on in relation to my question.
Yes, semplifying it's that way. What you say however happens only for a specific incidence angle, as I said, the Brewster's angle; at other angles, the light is not totally polarized (along the plane of the surface) but however is prevailingly polarized in that direction.
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In the following video the reflecting surface is in a vertical plane, so light reflected off it is prevailingly vertically polarized: a laser emits horizontally polarized light and the reflected light is very low, near brewster's angle:
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