wireless transmission via graphite coil

since graphite conducts. if spiral shape is drawn with pencil on the wall (thick , dark lines) will a voltage difference appear between inner and outer end of the spiral when a varying magnetic field is switched on, normal to wall my aim is to incorporate this into new mode of wireless data transmission

It is not a new mode, it is exactly how RFID works. So yes it will work, but graphite is very limited in how high a frequency you can use, you are better off using a printed circuit spiral or even a wire one.

Here is how I cut one once http://vimeo.com/14112968

Grumpy_Mike: So yes it will work, but graphite is very limited in how high a frequency you can use, you are better off using a printed circuit spiral or even a wire one.

why is graphite limited to low frequency

Because of the magnetic saturation parameter of the material.

Look at any inductor wound on a graphite core, there is a saturation / maximum frequency.

https://www.researchgate.net/figure/235964564_fig8_Figure-8-Graphite-saturation-curves-for-different-carbon-concentrations-in-C-O-H-fluids

And

https://en.m.wikipedia.org/wiki/Saturation_(magnetic)

Grumpy_Mike: It is not a new mode, it is exactly how RFID works. So yes it will work, but graphite is very limited in how high a frequency you can use, you are better off using a printed circuit spiral or even a wire one.

Here is how I cut one once http://vimeo.com/14112968

can graphite be adulterated to use at high frequency?

Yes, convert the graphite into nanotubes.

SumitAich: can graphite be adulterated to use at high frequency?

No. Why the obsession with graphite?

Graphite also has a fairly high resitivity, so it's efficiency as an antenna would be poor.

Allan