After reading about some of the photodiode characteristics on the internet I got really confused with the photodiode working principle. I tried to search for them in google , got some definitions , but it still confuses me a lot.
I found a topic on the internet which indicated that "photodiode is in reversed biased while LED is in forward biased" ?
So , is the reversed bias here photoconductive mode of photodiode ?
A problem that came to my mind is that , in the figure above , do i connect the longer lead of photodiode to ground or to the negative node of op-Amp ?
And does the current direction through photodiode is opposite to its indication in any mode (photoconductive or voltanic), for example like in picture above (photodiode "points up" while current goes from negative node to ground )?
Update 1 : thanks to excellent guys , i now understand a little more. But what i confused is the concept about the photoconductive mode . Is that true that any photodiode with voltage accross it different to 0 ( disequal 0) is in photoconductive mode ? Another question is that : if the photodiode is in photoconductive mode , if i change the polarity (example : anode initally connected to ground , now i changed : kathode to ground) , does the mode (photoconductive / photovoltaic) change too?