Suppose I have a standard credit card with a magnetic stripe, lying
- right on top of a cellphone, or
- in a regular leather wallet that's lying right on top of a cellphone.
The cellphone is on (but not in a call), uses a 3G network, and is in a good reception area.
Will the credit card be demagnetized (to the point where it can't be read) in the above 2 scenarios? If so, how long will it typically take? An answer that shows all assumptions and calculations used would be especially useful!
Mythbusters did this: http://en.wikipedia.org/wiki/MythBusters_%28season_1%29#Eelskin_Wallet
If I recall correctly, they tried rubbing cards with magnets and cellphones, but failed to cause any damage.