Question

At a certain location in the Philippines, Earth's magnetic field of 39 μT is horizontal and directed due north. Suppose the net field is zero exactly 2.0 cm above a long straight, horizontal wire that carries a constant current. (a) What is the magnitude of the current?

Answer 1

Answer:

the magnitude of current is 3.9 A

Explanation:

given,

earth magnetic field = 39 μT

                                 =   39 × 10⁻⁶ T

distance r = 2 cm

                 = 0.02 m

Using equation

                  $B = \dfrac{\mu_0 i}{2\pi r}$

                  $i = \dfrac{2\pi r B}{\mu_0}$

                  $i = \dfrac{2\pi\times 0.02\times 39 \times 10^{-6}}{\mu_0}$

                  $i = \dfrac{2\pi\times 0.02\times 39 \times 10^{-6}}{4\pi 10^{-7}}$

                                             = 3.9 A

hence, the magnitude of current is 3.9 A