Hey i have a mobile phone which has an magnetic accessory.Will this damage the phone in anyway??
If you're talking about a case with a magnetic closure, they are fine. They do not cause damage to the phone. I've been using them for years and have never had anything happen to my phone. I even have one right now for my Samsung t629. The magnets are strong enough to hold the case closed, but not strong enough to do any damage to your phone. That shouldn't be powerful enough to do any damage, but I also don't see the point in having that on my phone. My case that I have for the phone I have now has 2 magnets in the flap that are about 1 inch long and 1/2 inch wide. They are fairly good sized magnets and they don't do any damage.
A huuuuuuuuuge myth. No magnets damage mobile phones.
No more than a mag mount antenna on the trunk. No, should be no problem even in a moderately strong field. The very speaker in your phone has a sizable magnet as part of it's structure.
