I use the following formula to determine the impedance at the center of a resistor divider (the ADC input);
Code:
impedance = 1/( (1/rUpper) + (1/rLower) )
So in the case of a 10 KOhm pot', the highest impedance occurs when the wiper is in the center position;
Code:
rUpper rLower Impedance Position
-------------------------------------
5000 5000 2500 Ohms Center
1 10000 1 Ohm Full CCW
10000 1 1 Ohm Full CW
Here's a screenshot of my spreadsheet where I use that formula (I input Vin, R_upper, and R_lower values and the other values are caculated from those);
Kind regards, Mike, K8LH