What happens with the current in a circuit that is not consumed by any device?
What happens with the current in a circuit that is not consumed by any device?


If it is not consumed then it doesn't flow in the first place.


  Imagine I have an electronic circuit with one battery of 1,5 volts. I put a small light bulb of 1,5 volts too in the circuit that needs 0,01 amps to work. 


Assuming the bulb is rated for 1.5 V then from Ohm's law we know that the resistance is given by \$ R = \frac {V}{I} = \frac {1.5}{0.01} = 150 \ \Omega \$.


  Lets assume the current is 0,03 amps in the circuit (calculated from the Ohm Law). 


But it can't pass 0.03 A. It's resistance is too high. Effectively it resists the flow of current and limits it to 0.01 A.


  In order the light bulb not to burn with 0,03 amps, how does it to prevent from burning with these 0,03 amps when it only needs 0,01 amps?


Resistance!

My house is connected to the Irish national grid which has a peak generation capacity of 5 GW. What limits the current drawn by my 20 W LED lamp on my desk and prevents all 5 GW exploding beside my head? Answer: its resistance to current flow.