I have listen led work linear as in optocoupler so it use IR led
Will linearty work with IR led too?
And
2nd there is 2 string of led
A. The led of red 2v are connted in serious of 5 with series current R which is passing 20mA fixed
B. There is 16 led of red only same at 20mA with Rseries .
So will it brightness will same in a and b?
I think the current to light is linear with any color. (IR) Some white LEDs are using phosphor to get white. So they are a little different.
A LED with 2omA will out put the same light if it is in a string of 5 or a string of 2 or only a single LED.
So the 5 LED string (20mA) will output 5 time the light of one LED (20mA). Assuming the LEDs are all pointing at the light meter.