karnalta:
So we have I = 5 / 1, so the arduino should output 5 amp of current.. Not only 0.05.. I dont get it ..
Sorry if its a stupid question, but I am really beginning in electronic.
Yes, in ideal world it will be! And in ideal world if you put 0 (zero) ohm resistor you will have infinite current!
But world is real, so if you shortcut your output (or if you put a small resistor) the current will be limited by the maximum current that output can be supply.
This is the difference from ideal voltage source and real voltage source: Voltage source - Wikipedia