I don't know if I agree that the induced E field has no effect on a point charge. If it did not, induction would not work.
As far as verifying experimentally the 1/r effect at a point, I don't need to, do I?
"If it did not, induction would not work": this is the main point to verify. This objection is logical and I have already tried to verify it. If the induced E field has an effect on a point charge, then it has also an effect on charges in a small circuit not encircling the varying flux. To test it, I have used a toroid coil. On one side, near the toroid, I put two large metallic cylinders acting as capacitors. They were placed at some distance from each other and a wire connected the two capacitors with a voltmeter in series. All was placed in order that there is the presumed emf in the wire. But no voltage was measured. I have put an inductance in series with the wire to make the circuit more sensitive because resonant at the frequency used to power the toroid coil. Same null result. A voltage was measured only when the wire was placed through the toroid hole and the two capacitors at each end were near enough from each other. In this case I consider that the circuit was looped thanks to the displacement currents between the two capacitors. Note that if this effect of E=-dA/dt on a single charge was real, its corollary is that the reversed effect would also be possible, and so, we could induce an emf in a toroid coil from outside, without any conductor through the hole. I'm not aware that any experiment of this kind gave positive results. What I observe is the experimental impossibility to show any effect of E=-dA/dt on elements of circuit not encircling the flux and consequently the effect on a single charge is doubtful or too weak to be measured. I don't know (yet) why. This effect is indispensable to test the 1/r effect, otherwise with a closed circuit around the flux, we can only measure the well known trivial emf not depending on r.
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