Why has the LED gone dark?

Can someone tell why the LED has gone dark in this simulation. It seems pretty straightforward.

68 ohm resistor.

I think the answer is that the LED won’t change color because the LED part has no way to do that. It is likely the Voltmeter changing is the only change you will see because the voltmeter part was likely modified to display the voltage from the simulation. That said I haven’t played with simulation and may be wrong :slight_smile: .


Ok, am I missing something here? When I connect the cathode to positive it lights up but the voltage is negative 2.2v across the LED. Someone please tell me there is something wrong with the simulator.

Please try the examples that come with Fritzing. The LED goes dark because you connected it in reverse polarity. Since the LED blocks the current, there is no voltage drop at the resistor, and you see 3V at the LED, just how it should be.