commonjcb

Right, or we can just link to the physical law itself: - Lorentz force - the force on a current carrying wire. No need for a long wire. It's in the range of micro-Newtons for few Amps, for 10cm, at earth magnetic field:

https://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_curre...

"When a wire carrying an electric current is placed in a magnetic field, each of the moving charges, which comprise the current, experiences the Lorentz force, and together they can create a macroscopic force on the wire (sometimes called the Laplace force)."

The torsion balance introduces fixed biases, and can be operated only in XY plane. So in theory you're right, in practice it's not possible.

Not canceling earth's magnetic field (an easy thing to do) when measuring microNewtons at high currents is just very poor experimental practice. Unprofessional. Amateur.

Approximately the same distance as a good microphone can pick up the audio anyway. Read about near-field vs far-field:

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

Not this shit again...

Look closely at the picture of the test chamber in the article. Do you see Helmholtz coils surrounding the entire apparatus? Nope.

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

It's the same story as the EMdrive: they run something at high current, without cancelling earth's magnetic field.

high current + earth magnetic field = force. This method is used to move satellites:

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

It's probably by design, iPhones support magnetic-induction hearing aids, see here:

https://support.apple.com/en-us/HT202186

The are 2 standards, the old "telecoil" (direct) and the new FM loop, both operating at low frequencies...

Both work at very short ranges (inverse cube of the distance)