0
$\begingroup$

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?

$\endgroup$
2
  • 1
    $\begingroup$ 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. $\endgroup$ Commented Oct 15, 2022 at 9:40
  • 1
    $\begingroup$ @FlatterMann Please post brief answers as answers. Use comments to refine or improve the question. $\endgroup$
    – rob
    Commented Oct 15, 2022 at 9:43

2 Answers 2

1
$\begingroup$

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.

$\endgroup$
1
$\begingroup$

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.

Inside the LED the electrons in the circuit are giving up energy to electrons in the device. In detail, they are being pushed by the force on them (from nearby electrons in the wire, which in turn are pushed by the ones behind them, and so on around the circuit till you get to the battery) and they in turn push the ones in the device. The work done by this force provides the energy which first gets (momentarily) stored in the LED, and then it gets emitted as light when the electrons in the LED give up their energy.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.