I have a potentiometer of 10k and I connected it this way:
5v -> potentiometer -> analog input pin of Arduino
When I turn the potentiometer I change the resistance of the circuit but in the Arduino documentation they say that an analog pin in INPUT mode will have 1 megaohm resistance. So, for example, if I turn the potentiometer to the middle it will generate 5k of resistance + 1 megaohm of the analog pin it will result in a tiny, very tiny current. If I use U = R x I across the potentiometer it will be:
U = 5000 x 0.0000001
U ~ 0 across the potentiometer. So U will be 5 V at the analog input because there was no drop of voltage in the circuit. If turn the potentiometer all way up to 10k resistance the voltage in the analog input will also be 5 V because the voltage drop across the potentiometer is still really small.
I know that an analog pin in INPUT mode will read 0 V as 0 and 5 V as 1023. But as I showed you it should always read 5 V even when I turn the potentiometer all way up because the voltage is not being changed. I know I am wrong cause when I log the input pin it shows different values as I turn the potentiometer. So how does this work?