You can't change the Vf by shortening a Vf = 0.02 coil, hmmm?
Remarkable shortening of your own theory there.

Perhaps you might want to try again using real numbers. Simply
because you play the pity card of forgetfulness (blaming your reader
usually as a bluff) we will reprise the question once again:

Asked: At one length, one coil exhibits
Vf = 0.02,
reduce the coil length, what length for the SAME coil would that be
to render
Vf = 0.2
for instance?

1. We are not changing frequency;
2. we are not changing diameter/lambda
(nor in fact changing diameter OR lambda);
3. we are not changing pitch/lambda
(nor in fact changing pitch OR lambda).

SAME coil means the one being offered, and being shortened - all other
provisos stand