Is there a one-to-one relationship between active and passive voice in English, and what are reasons for using the passive rather than the active? plz answer in detail
In the working world, it is often more diplomatic to use the passive voice rather than the active if one needs to mention errors or oversights. By using this voice, no "finger pointing" is done and, therefore, the speaker exhibits more discretion.
Also, if the speaker really does not know for certain who the doer of an action is, then the passive voice allows the speaker to seem as though he/she is not intimating anyone as this subject. For example, if one has lost a textbook, which was on his/her desk, by saying "My book has been removed from my desk" the speaker points the finger at no one, and does not insult or enrage anyone.
I would add that in most if not all cases, a writer can take a passive voice sentence and make it active voice simply by having the "doer of the action" be the subject of the sentence. For example: The bone was chewed by the big dog. (Passive voice -- the bone isn't doing the chewing.) Changed to active voice: The big dog chewed the bone. (Active voice -- the dog is doing the chewing.) I think that in most cases, active voice writing is more clear and direct. It makes it very what is being done by whom. But as the previous posts suggest, there are circumstances where passive voice creates a specific tone that might prove useful.
As the previous poster mentioned, you might use more passive voice than active if you want to develop a tone of victimization or help the reader identify more with the person or thing being acted upon.
Generally heavy or exclusive use of active voice tends to create an intensity and a very different tone. I don't know that there is a one to one relationship between the two, as they are not always in direct opposition but serve different purposes in different contexts.
The main reason for using the passive voice, in my opinion, is to reduce the focus on the actor. You might do this, for example, if something bad has been done and you want to distract the reader from who did the bad thing and simply have them think about the fact that the bad thing happened.
You might also use the passive voice to make a character seem more like someone who is acted upon than an actor.