Question

Two long straight wires are parallel and carry current in the same direction. The currents are 8.0 and 12 A and the wires are separated by 0.40 cm. The magnetic field at a point midway between the wires is:_______a. 0b. 4 x 10^-4c. 8 x 10^-4d. 12 x 10^-4e. 20 x 10^-4

Answer 1

A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any point is specified by two values, the direction and the magnitude; such that it is a vector field. Mathematically it is described as,

$B = \frac{\mu_0 I}{2\pi d}$

Here

$\mu_0$=  Permeability at free space constant

$I_{1,2}$= Current at each object

d = Distance to the center point of the two object

Two magnetic field due to the current in the same directions then is,

$B = \frac{\mu_0 I_1}{2\pi d_1}+\frac{\mu_0 I_2}{2\pi d_2}$

Replacing,

$B = \frac{(4\pi *10^{-7})(8)}{2\pi (2*10^{-3})}+\frac{(4\pi *10^{-7})(12)}{2\pi (2*10^{-3})}$

$B = 8*10^{-4} +12*10^{-4}$

$B = 20*10^{-4}T$

Therefore the correct answer is E.