Credit-Card Magnetic Strips Experiments carried out on the television show Mythbusters determined that a magnetic field of 1000 gauss is nee

Question

Credit-Card Magnetic Strips Experiments carried out on the television show Mythbusters determined that a magnetic field of 1000 gauss is needed to corrupt the information on a credit card’s magnetic strip. (They also busted the myth that a credit card can be demagnetized by an electric eel or an eelskin wallet.) Suppose a long, straight wire carries a current of 7.0A . How close can a credit card be held to this wire without damaging its magnetic strip?

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Thiên Di 4 years 2021-09-03T05:55:55+00:00 1 Answers 16 views 0

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  1. Acacia
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    2021-09-03T05:57:47+00:00
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    Answer:

    14 μm

    Explanation:

    The magnetic field due to a long straight wire is B = μ₀i/2πr where  μ₀ = permeability of free space = 4π × 10⁻⁷ H/m, i = current = 7.0 A and r = distance of credit card from magnetic field.

    So r = μ₀i/2πB since B = 1000 gauss = 1000 G × 1 T/10000 G  = 0.1 T

    r = 4π × 10⁻⁷ H/m × 7.0 A/(2π × 0.1 T)

    r = 2 × 10⁻⁷ H/m × 7.0 A/0.1 T

    r = 14 × 10⁻⁷ H/m × A/0.1 T

    r = 140 × 10⁻⁷ m

    r = 1.4 × 10⁻⁵ m

    r = 14 × 10⁻⁶ m

    r = 14 μm

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