Re: [Phys-L] RLC lab

[bernard cleyet <bernard@cleyet.org>]

> On 2022/Apr/18, at 13:11, Brian Whatcott <betwys1@sbcglobal.net> wrote:
>
> We might suppose that the large inductor is close-wrapped, so that the interwinding capacitance largely cancels the inductive reactance at say 1 kHz leaving 60 ohms contribution in a series circuit of 60 ohms, 188 ohms due to the capacitor at 1 kHz, and 100 ohms, a total of 348 ohms so that the coil contributes  60/348 of 5 volts = 0.9 volts of the volts drop.


Such an inductor is not a ”pure” inductor, as BW points out.  Not mentioned is most of the inductance is due to the ferromagnetic core.  Does the  µ change W/frequency?  The intermediate lab. at UCSC includes the ”Low Frequency Impedances”.  I don’t remember, but I suspect this one is included.  I remember specifically one box that contains a heavy wire, with four terminals.  Eventually the students discover a multi-amp. supply in the cabinet.  For the experienced the four terminal is a clue.  Of course, the cabinets include many d’Arsonval meters, 500 series Teks on carts, and L&N oscillators.  (Lab created ~ 1966)


bc ….  over 25 years since.  


A BTW:  When I retired we still used a 500 for the ESR/EPR experiment, because it had an output of the sweep.  It, of course, included a phase sensitive detector/lock in, and the set up was superior to many others, because the samples were placed in a tunable cavity instead of a wave guide.  It was set up by Bud Bridges, whose early research used a traveling wave oscillator and much other microwave "stuff”. I added an ADC, so could be downloaded to computer analysis.