Two long anti-parallel current-carrying wires carry currents of 20 A and 5.0 A. If the wires are separated by 20 cm. Find the magnitude of the magnetic field a point equally separated between both wires.

5 x 10⁻⁵ T

Explanation:

Magnetic field at a point d distance away from a current carrying wire having current of I

B = 10⁻⁷ x 2I / d

Here magnetic field due to current of 20 A

B₁ = 10⁻⁷ x 2 x 20 / 10 x 10⁻²

= 4 x 10⁻⁵ T .

Here magnetic field due to current of 5 A

B₂ = 10⁻⁷ x 2 x 5 / 10 x 10⁻²

=  10⁻⁵ T .

These magnetic fields are acting in the same direction

Total magnetic field

B = B₁ + B₂

= 4 x 10⁻⁵ + 10⁻⁵ = 5 x 10⁻⁵ T .

because if the tool that you are using is not balanced it there would be false mass.