I've a couple of basic, but fundamental for me questions, and I will be really appriciated if someone drop me a line about them
In a simplest demo DigitalReadSerial(http://arduino.cc/en/Tutorial/DigitalReadSerial) there is a pull-down resistor. I understand it purpose, but not clearly understand what current can flow in it while button is unpressed (is pin, configured as input have some voltage on it)? And why value is 10K, how it was calculated?
When button is pressed in this demo it seems that pin is connected directly to 5V. Why Arduino is not short-circuit? Can I wire digital\analog input directly to 5V without any resistor?
Next simplest demo AnalogReadSerial (http://arduino.cc/en/Tutorial/AnalogReadSerial). In one of extreme pot positions (it depends how I hook resistor to the circuit left or right) pin A0 seems to be connected direcly to 5V without any load. But connection between 5V and GND always loaded on 47K. Right?
Thanks in advance!
P.S. Pages on I\O in "Foundation" section (http://arduino.cc/en/Tutorial/DigitalPins) are very clear, but these questions left in my head :)