Question

Two parallel wires are horizontally oriented. The top wire has current of some value I directed to the left, and the bottom wire has current of 2 x I directed to the right. At what point will the magnetic fields cancel out?

a. Some point between the two wiresb. Some point above the top wirec. Some point below the bottom wired. No position cancels the magnetic fields

Answer 1

b. Some point above the top wire

Step-by-step explanation:

Given:

• current in top wire,
  `I_t=I\ A`

• current in bottom wire,
  `I_b=2I\ A`

Given that the current in the top wire travels left and the current in the bottom wire travels right.

The magnitude of magnetic field is given as:

`B=(\mu_0.I)/(2\pi.r)`

where:

r = radial distance from the center of the wire

`I=` magnitude of current in the wire

`\mu_0=` permeability of free space

Now using Maxwell's right hand thumb rule we determine the direction of the magnetic field around the wire. So, we can deduce that this point will be above the top wire because they are in the opposite direction.