Can a cellular phone demagnetize a credit card?

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Discussion Overview

The discussion centers on whether a cellular phone can demagnetize a credit card, exploring the electromagnetic interactions involved and the effects of phone operation on credit card functionality. It includes inquiries about the nature of electromagnetic waves emitted by phones and their potential impact on magnetic materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that while a speaker can demagnetize a credit card, the small size and shielding of cell phone speakers likely make this occurrence rare.
  • Another participant explains that when a phone rings, it transmits at high power briefly to communicate with the tower, which may have implications for its electromagnetic output.
  • A participant references a related experiment by the MythBusters, indicating a possible connection to the topic but does not provide details.
  • Another participant notes that a significant magnetic field strength is required to reorient the magnetic dipoles on a credit card strip, questioning whether the output from a cell phone is sufficient for this effect.

Areas of Agreement / Disagreement

Participants express varying opinions on the likelihood of a cell phone demagnetizing a credit card, with some suggesting it is possible under certain conditions while others remain skeptical about the effectiveness of a phone's electromagnetic output.

Contextual Notes

There are unresolved questions regarding the specific electromagnetic output of cell phones and the threshold required for demagnetization, as well as the conditions under which this might occur.

Who May Find This Useful

This discussion may be of interest to those exploring electromagnetic theory, the functionality of credit cards, and the interactions between electronic devices and magnetic materials.

Feynmanfan
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Hi there!

Can a cellular phone demagnetize a credit card? Why do loudspeakers make a strange noise when the cellular phone rings?

I don't know the physical explanation to all this. I'd be grateful if you could tell me what kind of electromagnetic wave phones radiate and how they works.

Thanks
 
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1) A speaker can demagnetize a credit card. Since cell phones have speakers, it's conceivable that this can happen. On the other hand, the speakers are quite small, and probably shielded pretty well, so I'd bet it rarely happens.

2) When your cell phone is about to ring, the tower sends out a message checking to see if your phone is available. Your phone responds with a message saying it is available, at its highest transmission power. This occurs a half second or so before your phone actually begins to ring. Your phone rarely transmits at its highest transmission power, but does so during this phase of the call to make sure the tower hears it.

- Warren
 
Didn't the myth busters do something like this? Oh wait that was with ele skin walets.
 
Thank you, Warren
 
It takes a pretty large H field to reorient the magnetic dipoles on the strip.
My degausser uses at least 50 watts to do the job in a 6" torus field at 60 Hz.
Maybe if you held them tight together ... ( H is 1/r )
I can't quantify it but what is the cell putting out ... a watt or two ?
And might not this be above a cutoff frequency for reorientation ?

Best
 

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