# Will a circuit be closed if we make a 100% efficient LED?

Suppose we make a LED that is 100% efficient, that is, it converts 100% of electric current we supply to light. Based on my understanding of electric current, as there is no current flowing back to the battery/cell/electric power source the circuit should be open (because 100% of the electric current is converted to light), i.e., the circuit cannot be closed and therefore, such a LED cannot exist.

Is my understanding correct or incorrect?

• Charge conservation requires that the current in a simple conductor loop is the same everywhere. Since light does not contain charges, there is no loss of charge in a circuit with an LED of any efficiency. Commented Oct 15, 2022 at 9:40
100% efficient means the electrical energy (not the current) is converted into light energy. The electrical energy per unit time, i.e. power, delivered to the LED is $${\rm power} = V \times I$$ where $$V$$ is the voltage across the LED and $$I$$ is the current through it. In an inefficient LED some of this power goes to heating the LED. In an efficient one it all goes to emitted light.