I've been doing a bit more experimentation today :shocked:
I repeated the measurements a bit later & found using the same holes, although the resistance remained the same, the capacitance had reduced a bit. Cleaning the prods & inserting them in new areas nearby still produced these new readings. All I can think that the cold potato was now a bit warmer now it had been indoors for a few hours.
Anyway I found moving the prod insertion points closer increased the capacitance to such a point that the prods one cm apart had nearly double the capacitance of the prods at the furthest point. So a better result could have been achieved if the AA man had put the screws nearby to each other.
The curious thing is that wherever I inserted the prods be it, near to each other, on opposite sides across the width or the length the resistance remained constant.
Next I tried a carrot & this behaved in the same way with capacitance being greatest with the prods nearby. But the resistance remained the same here on both measurements as 1.1 megohms.
I measured the capacitance as 0.08 mfd with the prods close by then chopped the carrot & it remained at 0.08 mfd
So as far as vegetables go, size or even length does not matter :-D
Looks like I'll be eating perforated vegetables tonight :shocked: