Faraday Demo

Awesome. What is the name of the site?

Thanks, Fredski, that was fascinating.

I actually tried to do this one time with glass mirrors. If you have a substance like sugar solution that rotates the plane of polarization, when the light reflects back the other way, the rotation gets undone. With the Faraday effect, it continues to rotate.

I placed two back silvered mirrors facing each other and slightly offset so I could shine a light through a polarizer and reflect zig zag between the mirrors (through the glass) and through another polarizer when it exited. I placed this against the pole of a strong Neodymium magnet. I thought I could see a weak effect when the magnet was close by, but I'm not sure. The believe effect was too weak in the type of glass the mirrors were made of.

I need to go check to see if my wife has any olive oil...

Extra virgin?

A simple explanation of what's happening:

"The Faraday effect is caused by left and right circularly polarized waves propagating at slightly different speeds, a property known as circular birefringence. Since a linear polarization can be decomposed into the superposition of two equal-amplitude circularly polarized components of opposite handedness and different phase, the effect of a relative phase shift, induced by the Faraday effect, is to rotate the orientation of a wave's linear polarization."

"The linear polarized light that is seen to rotate in the Faraday effect can be seen as consisting of the superposition of a right- and a left- circularly polarized beam (this superposition principle is a fundamental in many branches of physics). We can look at the effects of each component (right- or left polarized) separately, and see what effect this has on the result.

In circularly polarized light the direction of the electric field rotates at the frequency of the light, either clockwise or anticlockwise. In a material, this electric field causes a force on the charged particles comprising the material (because of their light mass the electrons are most heavily affected). The affected motion will be circular, and circularly moving charges will create their own (magnetic) field in addition to the external magnetic field. There will thus be two different cases, the created field will be parallel to the external field for one (circular) polarization, and in the opposing direction for the other polarization direction - thus the net B field is enhanced in one direction and diminished in the opposite direction. This changes the dynamics of the interaction for each beam and one of the beams will be slowed down more than the other, causing a phase difference between the left- and right-polarized beam. When you add the two beams after this phase shift, the result is again a linearly polarized beam, but with a rotation in the polarization direction."

https://en.wikipedia.org/wiki/Faraday_effect

Here is a paper written on measuring the Verdet constant for olive oil. The Verdet constant of materials is very wavelength dependent, and at certain wavelengths olive oil compares favorably with the best Faraday rotator materials.

http://www.sestindia.org/wp-content/uploads/2013/12/Volume-2Number-3PP-362-368.pdf

Thanks, great channel....

I did something a little similar in 1964, rotating the plane of polarized light in a cell filled with pure aniline, called it a Kerr Cell

I used it to q-switch a xenon pumped ruby cavity, which was pumped to maximum inversion with optical rotation blocking the laser cascade,and then a pulse generator pulsed the cell to create a short pulse and empty the inversion.

I could get as many as 20 flashes from the duration of a single xenon flash.

This laser light was doubled in anon-linear media to create an ultraviolet flash that was used to illuminate the fluid phase in a heart valve model, close to the wall. The fluid was matched rheologically to blood, with tiny spheres the size of blood cells made of the polymerized fluid to optimize the match, but to be transparent to the source and emitted light by having the same refractive index. The object was to find the shear profile from the bulk to the wall so the heart valve could designed to minimize shear induced aggregation of cells. We used the clear runs to design the passage and then operated it with beef blood to test for real. This was a problem, because we could not use clot blockers, so we had to use fresh blood for the run, which ran for 30 minutes and then a clot blocker prevented further clotting, but the clots already made would persist, and the blood was run through a low pressure millipore filter and clots counted by eye.

This was sponsored by Connaught labs, now Sanofi Pasteur and the results went one to optimize a number of blood handling things that got implanted.

As similar effect occurs in a magnetic field. The magnetic form is speed limited by the induction. The Kerr cell could rotate the beam 90 degrees in less than 2-3 ns

The Kerr effect is mentioned in the end of the video. Interesting information.

Thanks for sharing, I was fascinated.

That Guy is also a brilliant teacher, covering EVERYTHING in an easy to understand manner...

Few on CR4 achieve that!!!

Excellent video, I'll have to look at a few more there. Another source of interesting, well presented videos is the Royal Institution video site. A lot of them are aimed at a young audience which makes them suitable for us.

How true!!

I loved the part where he smashed his fingers with the rare earth magnets, I have done that myself several times. They are awesome magnets and fun to play with.

If you get them close to each other, watch out. I have seem them attract so fast that one of them can shatter when they come in contact with one another.