It is the same question which I have mentioned at On-topic question about wavelengths. It took several edits for the question to be reopened. Yet, my question has 6 downvotes and 1 upvote. Apart from all the edits that I made to reopen the question, what further improvements not prevent the question from getting downvotes.
Downvotes mean, according to the tooltip when you hover over the button, that the question is unclear or not useful. Users have also described using downvotes to indicate that a question shows a lack of research effort, or that they think the question is off-topic.
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Users are not required nor expected to publicly explain their votes, so for a detailed explanation of the votes you are out of luck unless a voter volunteers. Try not to worry about it too much; just ask better questions on the future.
This version of the question is unclear: you can get an answer in most textbooks, web sources (such as this one) or in many videos. So what exactly do you want?
If not for the bounty, the current version of the question would likely be closed again.