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Re: [Phys-L] e/m apparatus




On 2017/Jun/08, at 09:47, Dan Beeker via Phys-l <phys-l@mail.phys-l.org> wrote:

I so miss the old Sargent Welch apparatus. It was the first “experiment” I did in my first time teaching first year e&m. There was fascinating amount of physics and when you minded your 'p's and ‘q’s with the right instruments you got 1% or so results. It was the lab that inspired my students to work through the tough spots and keep at it when nothing seemed to work right. Was a fine lab for measurements. Our apparatus had big (1m?) coils to cancel the earth’s magnetic field. iirc they had square conductors that were carefully wrapped to get a tight coil. They may have been rewound but suspect they came that way from SW. Made a difference which side of the heater was grounded as well as whether one used ac or dc for the heater. The tube was big enough to easily see the beam and make measurements. Correcting for refraction through the glass tube was also a challenge. I suppose working with high voltages carries too much liabiity but they are so rich in phyisics concepts I would love to see the things reappear, even if they are used in the advanced labs. I so wish they would have a reincarnation.

Dan


High joltage? According to the Welch instructions < 50V.

It was discontinued from the intermediate lab, so I gave it to a HS in SoCal.


bc found UCSC’s instructions; several pp. including a discussion of the broadening of the beam.