A long straight wire carries a current of 35 A. The magnitude of the m…

Question

A long straight wire carries a current of 35 A. The magnitude of the magnetic field at a point 20 cm from the wire is:

Accepted Answer

C. 3.5 × 10⁻⁵ T

1. Field of a long straight wire: $B = \dfrac{\mu_0 I}{2\pi r}$.
2. Write $\dfrac{\mu_0}{2\pi} = 2	imes10^{-7}$ T m A⁻¹.
3. Substitute $I = 35$ A, $r = 0.20$ m: $B = \dfrac{2	imes10^{-7}	imes35}{0.20}$.
4. Numerator $= 7	imes10^{-6}$; dividing by 0.20 gives $B = 3.5	imes10^{-5}$ T.
_Source: syllabus Physics Ch 4 "Moving Charges and Magnetism", p.158_

Answer

1.75 × 10⁻⁵ T

Answer

7.0 × 10⁻⁵ T

Answer

3.5 × 10⁻⁴ T

A long straight wire carries a current of 35 A. The magnitude of the magnetic field at a point 20 cm from the wire is:

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