Metal Detectors Could Calculate How Much Cash You Have With You | The State

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It has long been suspected that the security strips found on US banknotes allow government agencies use metal detectors to figure out how much cash you’re carrying.

In fact, these tapes are already used by some vending machines to verify the authenticity of a ticket; and physicists Christopher Fuller and Antao Chen of the University of Washington in Seattle said that large bundles of banknotes could contain enough magnetic material to be remotely detected, and thus allowing the police to catch people trying to smuggle cash across the border.

Physicists found that An ordinary handheld metal detector could detect a $ 1 bill from 3 centimeters away, and placing the bills behind materials like plastic, cardboard, and cloth doesn’t really do much to block the signal, as reported in NewScientist.

The scientists also noted that, as more bills were added in amounts of $ 5, the signal strength increased, which means that it is possible to count the number of banknotes, although it would still be difficult to know the total value in dollars, since banknotes of different denominations contain the same amount of magnetic tape.

Using larger metal detectors, such as those found in airports, should also increase the detection range, although detecting banknotes in such situations would be more difficult, as many other sources could interfere with the signal.

“In a real situation, the signal will be ‘noisy’ and some form of digital signal processing may be necessary,” Chen said.

It should be noted that some experts have said that if equipment is added to detectors to capture other aspects of the signal, a more detailed analysis could be made of the number of bills that a person could carry.