I'm a newbie in electronics and I would like to what is the luminosity of standard RED led. Kindly reply asap. thanks!

 

It may depend on LED manufacture types...

 

Welcome to AAC!
The datasheets for specific LEDs will have the answer. There isn't a 'standard' that I'm aware of.

 

Ditto the welcome to AAC!

Luminous intensity is dependent on LED type and current. Manufacturers typically specify at 20mA.

If you need to know intensity of an unknown LED, you can use a sensor to measure. I've used products from TAOS.

 

What you can do is go to a vendor site like digikey.com, mouser.com, etc., and search LEDs. For example, if you go to mouser, go to Optoelectronics -> Led Indication -> Standard LEDs (through hole), and select the color Red. That narrows it down to 1339 choices, with luminous intensities from 0.1 mcd to 65000 mcd. Intensity is a function of how tightly the light is focused, of course. An LED with a narrow viewing angle will have high intensity compared to the same thing with a wide viewing angle. It could be the same physical LED die inside a package with a different lens, that's all.