A semi-infinite wire runs along the positive y axis, beginning at the origin (x = y = 0)and extending infinitely far in the +y direction.If the current in the wire is 12 A, what magnetic field does it create on the x axis at the point x = 3.5 cm? A)0 T B)3.4 x 10^-5 T C)6.9 x 10^-5 T D)1.4 x 10^-4 T E)4.3 x 10^-4 T

Question

Quizplus · Accepted Answer

The magnetic field created by a straight current-carrying wire at a distance r from the wire is given by:
B = μ0I/2πr
Where μ0 is the permeability of free space (4π x 10^-7 Tm/A), I is the current, and r is the distance from the wire.
Since the wire is running along the y axis, the magnetic field will have no x component and only a y component. At the point x = 3.5 cm, the distance from the wire is r = 3.5 cm.
Therefore, plugging in the given values, we get:
B = (4π x 10^-7 Tm/A) x (12 A)/2π(3.5 x 10^-2 m)
B ≈ 3.4 x 10^-5 T
Converting to scientific notation, we get 3.4 x 10^-5 T = 3.4 x 10^-1 µT = 3.4 x 10^-1 x 10^-6 T = 3.4 x 10^-7 T.
Rounding to two significant figures, the answer is B) 3.4 x 10^-5 T.

A Semi-Infinite Wire Runs Along the Positive Y Axis, Beginning