what dependence does the intensity of a normal LED(the one used for DIY projects) follow with respect to distance?

Can someone explain what's wrong with it? Otherwise, let's reopen.


4 Answers 4


That question was crap and stupid and not about electrical engineering. It looks better after some edits, but here is the entire original question text:

I need the dependence of my led(approximate dependence) with respect to distance for a project I'm working on. I am guessing that since the LED inside the glass pane is somewhat like a wire thus it might follow inverse proportion with distance. Is this right? If not, then please give some details of the right proportionality.

Despite the title, this has nothing to do with the light source being a LED. This is a very basic high school physics question.

It was also very poorly written. In this case it seems the very poor writing (to the point of being unclear and quite annoying to read) was due to unfamiliarity with English as apposed to sloppiness. That's not the OP's fault, but then again, it's not our fault either. Reading bad English is annoying and confusing regardless of why the English is bad.

Everyone in the world doesn't have a right to post here just because it's not their fault they can't write English. We have to have some minimum standards. Someone can edit this question, guessing what the OP really meant, go back and forth a few times with questions in comments, and maybe eventually arrive at a good question. However, that puts a lot of burden on the volunteers here and noises up the site by constantly bumping a crappy question to the top of the list. Even if all that worked, now the OP will be back doing the same thing again. Basically, we simply don't want this guy here. The cost/benefit just doesn't make sense.

The real problem here is that you posted a good answer to a crappy question, and now you're complaining when the inevitable happened. Don't do that. You should have known better. You're getting what you deserve.

If you want to post a writeup like you did, ask your own well-written question and then answer it yourself. That's perfectly within the site quidelines, solves your problem, but doesn't hurt the site in the process. Actually you could still do that. Write a good question targeted at your answer, copy your answer to it, then flag a mod to delete the whole original question.


I think this is a reaction to the pool of other poor quality questions. Maybe this one has a good chance of being improved (certainly there is a good answer), but as it stands the question lacks both focus, and signs of any effort elsewhere.

It sounds like the sort of question a 14 year old would ask over breakfast based on an observation, rather than a genuine problem that someone has encountered in the course of their development.

I think it is better to insist that the question is improved before providing answers - but the standard of the comments is borderline (not sure any rate being flagged).

Bottom line, few of the active community will be competent teachers, and I'm sure we're all sick of being asked weak questions all day long.


I personally voted to close (with a few hesitations). We see more or less what is being asked at the beginning, but then, in the description, the user asks whether the "LED inside the glass pane is somewhat like a wire" or "a point source", and apparently, that would completely change the result.

So then, it becomes rather unclear. Why the OP thinks the shape of the lighting element would have such an importance? So I get confused, not sure I actually guessed right what I thought was the question initially, and follow the move of closing because I don't see how someone could address all the misunderstandings in this question, let alone the way it is formulated.

Actually, if the question had been shorter, with less inconsistent assumptions from the OP, I wouldn't have closed it.

But you made a great answer, I sure upvoted that 1 (just, I think you could actually have clarified this wire/point misconception in it 2).

1 - and to be fully transparent: I also upvoted this very question because I think it's good to ask, but downvoted your answer in it because I fully disagree with it.

2 - but it's hard to clarify that part because we don't understand how the OP came to see things that way - that's my point.

  • \$\begingroup\$ Isn't Olin right though? It's fundamentally a (very basic) optics question... which has nothing to do with EE directly. Semiconductor device physics questions I get... but talking about how light spreads out in space isn't EE. \$\endgroup\$
    – Daniel
    Jun 29, 2016 at 0:14
  • \$\begingroup\$ @Daniel yes, he's right. But I did not mention it because actually, I've been fooled by the LED formulation and didn't even notice it was also off-topic. \$\endgroup\$
    – dim
    Jun 29, 2016 at 5:14

Given, no feedback and additional downvotes, I think I found the answer...

It's just the EE.SE "culture"

New user asks reasonable question in full compliance, but with some ESL issue.

Relatively new low rep user (but occasionally very high-rep user) shows up to offer criticism of OP and vote to close (probably because that's how they were treated coming up the rep food-chain).

Question is improved to comply with the original ask.

More mindless bullies show up to pile on.

...so not only can they not help the OP, but they can make sure that no one can help the OP.

Next time you're thinking about vote-to-close, stop and ask yourself if that's the kind of mentor you want to be.

  • \$\begingroup\$ Well, "no feedback" because you didn't wait long enough, maybe. People don't check meta every two minutes. \$\endgroup\$
    – dim
    Jun 28, 2016 at 10:27
  • 4
    \$\begingroup\$ Also, I don't think the tone used in your answer here is appropriate. And the substance of it is wrong. 1) I am indeed very new here, and I never felt that "rep food-chain" you describe. 2) The "intensity led" question has seen some edits, both from the OP that just added some more confusion, and from you that were mostly cosmetic changes, but it is still unclear. 3) I don't close to teach a lesson to newcomers, but simply because I feel the question does not comply 4) I don't plan to become a mentor to anyone. \$\endgroup\$
    – dim
    Jun 28, 2016 at 11:42

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