Here, without much comment, we offer up some initial thoughts and experimental results…
Experimentation was done using a pair of hand-turned copper coils formed on PVC drainpipe, of nominal diameter 10cm. Both coils had 50 turns. The first coil was driven directly from a signal generator* which was capable of a range of frequencies up to about 20 kHz. The second coil was attached to an AC voltmeter and had the possibility of adding a range of capacitors (from 0 μF up to 5 μF) across it in parallel.
(* The signal generator we used was actually just a laptop with a modified speaker. The speaker cone had been removed and replaced with a pair of 4mm sockets.)
The software we used to drive the speaker was called ‘Scope’ by Christian Zeitnitz. It is free for personal use and is a great piece of software – it can turn your PC into an oscilloscope or a signal generator – or both at the same time!
Although in theory we could use two speakers at the same time, since all sound cards have a stereo output, we decided not to in case the power amplifier inside our $15 modified speakers suffered from any kind of crosstalk between channels.
Angular separation of coils
Transverse (lateral) displacement of coils
Longitudinal displacement of coils
Effects of placing capacitors across the second coil
So, what happens if we vary the capacitance across the secondary coil?
Relating this back to theory…