What happens to an LED when current flows in the reverse direction?

When current flows in the reverse direction through a light-emitting diode (LED), it typically remains off. LEDs are designed to allow current to flow in one direction only, known as the forward bias. In the reverse bias condition, very little current can flow, usually only a small leakage current. If this reverse voltage is within the manufacturer's rating, the LED will not emit light and will appear off. This characteristic prevents damage to the LED in typical applications, as they are generally tolerant of small reverse voltages up to a certain limit, known as the reverse breakdown voltage.

If the reverse voltage exceeds this limit, there is a risk of breakdown, which could damage the LED and potentially cause it to burn out, but this is not the typical behavior under normal conditions. The LED's ability to remain off when reverse-biased is a fundamental property that distinguishes it from other components in a circuit.