Hi all, I need some help on the following question:

A blue LED is emitting a 470nm light at a measurable output power of 16mW while the current of the device is 20mA. Calculate the external quantum efficiency of the LED. (1eV = 1.6*10^-19J, electronic charge(e) = 1.6*10^-19C)

I know this is not very related to electronic circuit, but I don't have a better place to seek for help.

Thanks all.

 

How is the external quantum efficiency defined?

 

I know this is not very related to electronic circuit, but I don't have a better place to seek for help.

There are 226,000 sites that refer to external quantum efficiency.

https://www.google.com/#q=+"external+quantum+efficiency+"

and adding LED to the search you reduce that to 143,000

https://www.google.com/#q=+"external+quantum+efficiency+"++"LED"