# Faraday Rotation Effect Lab -- sources of components...

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## Main Question or Discussion Point

I appreciate the link to the field strength calculator. http://www.calctool.org/CALC/phys/electromagnetism/solenoid
I'm also looking for recommendations on sources for magnets. What I'm trying to do is put together a Faraday Rotation Effect Lab.

This is my Faraday Rotator, a 12 cm x 2.0 cm cylinder of something close to flint glass with a half decent Verdet Constant.

Does anyone have pointers to a lab supply company with solenoids capable of 0.5T or higher?

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CWatters
Homework Helper
Gold Member
Not really my subject but I think it would be difficult to generate a field of 0.5T in that tube. For example at 1A I calculated you would need 95,400 turns of wire. At 100A it's 954 turns.

mfb
Mentor
400 kA/m assuming µr of about 1, with a length of 12 cm we need 50 kA ring current.

Let's check 5000 turns at 10 A: With 2 cm diameter, the wire has a length of 314 meters. To limit heat dissipation to 100 W with copper, voltage has to be 10 V, which means 1 Ohm resistance, which needs 5 mm^2 wire cross section. At 2.5 mm between adjacent windings, only 48 windings fit next to each other, so you need 100 layers which makes the coil 25cm thick (in radius). Uhm...
The 10 A were arbitrary, but the conclusion doesn't change if we plug in other values: Double it and you half the voltage, which leads to 1/4 the resistance at 1/2 the total length, so cross-section goes up by a factor 2 and we arrive at the same thickness again.

Very short pulses would allow a higher power dissipation, integrated cooling helps as well. Superconducting coils can easily provide such a magnetic field. All those solutions exist commercially, but they are quite expensive.

CWatters