Sorry this is such a silly question, but I can't seem to understand this. In the third diagram here it shows a pull-up resistor.
I understand that when the switch S1 is closed, current is pulled down to ground and assumes a value of 0. This doesn't short because of the resistor limiting the current.
My question is: When the switch is open and the current is flowing into the input pin of the device, how does it pick up that this is a high value and not a low value? Wouldn't the resistor limit it to the extent that it would be .0005 A and so it would barely register with the device?
EDIT: Also, I am just looking at the pull-down resistor case on the same page. Why does the first switch not short when it is directly connected to VCC, there is no resistor, and the switch is open? Isn't this a no-no? I can't really grasp what is going on with the pull-down resistor.