Why Does Negative Current Occur in LEDs at Low Voltage?

[Superman234]

Hi,
Why is there negative current in an LED at low voltage(set up in forward voltage)?
Why is there luminescence of an LED at negative current as described above(when LED is in forward voltage)?
How would the I-V curves of LEDs of different colours vary? Why?

The questions I've asked all resulted from an experiment that I did. and yes, I did the experiment several times with 5 LED's and still had some unexplained things...

Thanks

 

[mfb]

Please show your experimental setup.

LEDs (and all other electronic objects) always have some leakage current, in the same direction as the potential difference.

How would the I-V curves of LEDs of different colours vary? Why?

Different colors need different voltages to start conducting (significant currents), as different colors correspond to different band gaps.