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Question
The magnetic field at a distance of 2.4 cm from a long straight [current-carrying] wire is 16 µT. What is the current through the wire?
Solution
Data: a = 2.4 x 10-2 m, B = 1.6 x 10-5T,
`mu_0/(4pi) = 10^-7`T m/A
B = `(mu_0"I")/(2pi"a") = mu_0/(4pi) (2"I")/"a"`
The current through the wire,
I = `1/(mu_0//4pi) "aB"/2 = 1/10^-7 = ((2.4 xx 10^-2)(1.6 xx 10^-5))/2` = 1.92 A
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