If you downvote with a valid explanation, I really don't think you will fall foul of serial downvoting. There's so many questions on the site that concern say electromagnetism that we're bound to see some similar answers. It's a fact of life. And of course, you could always refer to those similar answers. In addition you could spread your activity over a few days. On top of that it might help if you could refer here to examples of this "serial answering" so people can gauge the situation for themselves. Do note that answering questions is what Physics Stack Exchange is all about.
Another thing you could consider is giving a better answer that explains things in a superior fashion. If your answer has sufficient clarity and logic it will surely show why the other answer is wrong without any descent into unseemly unprofessional animosity. I would urge you to put some effort into this, because in my experience it can be most rewarding. Feynman was known as the great explainer, and there's a saying which is sometimes attributed to Einstein: "You do not really understand something unless you can explain it to your grandmother". I think it's true. We might think we understand something, but if we can't actually explain it, then we don't. So if you find yourself struggling, you need to stop and think. Particularly if the other answer is clear and simple, and refers to Maxwell/Minkowski/Einstein/Jackson/etc. If your answer is as clear as mud, or is full of "it just is" mathematics that confuses field and force, or says these guys are wrong, it's possible that your answer is wrong.
Don't discount this possibility. We are all wrong from time to time. Knowing this and admitting to the possibility is what distinguishes the scientific community from a medieval theocracy. Indeed, it's why we have scientific progress. Remember: it's the Physics Stack Exchange. Not the Spanish Inquisition.