Question

The two wires shown in the figure below are separated by d = 11.1 cm and carry currents of I = 4.65 A in opposite directions.

(a) Find the magnitude and direction of the net magnetic field at a point midway between the wires.

(b) Find the magnitude and direction of the net magnetic field at point P1, 11.1 cm to the right of the wire on the right.

(c) Find the magnitude and direction of the net magnetic field at point P2, 2d = 22.2 cm to the left of the wire on the left.

Answer 1

a)

Both Magnetic fields point out of the page ,So net magnetic field

B = (4pi*10^-7)(4.65)/(2pi)(0.111/2) + (4pi*10^-7)(4.65)/(2pi)(0.111/2)

B = 3.35*10^-5 T or 33.5 μT

Direction is into the page

b)

The Magnetic field from the closer wire will point out of the page, but from the farther wire it will point into the page, therefore Net magnetic field is

B =  (4pi*10^-7)(4.65)/(2pi)(0.111) - (4pi*10^-7)(4.65)/(2pi)(0.111*2)

B = 4.19*10^-6 T  or 4.19 uT

Direction is out of the page

c)

The Magnetic field from the closer wire will point out of the page, but from the farther wire it will point into the page, therefore Net magnetic field is

B = (4pi*10^-7)(4.65)/(2pi)(0.111*2) - (4pi*10^-7)(4.65)/(2pi)(0.111*3)

B = 1.4*10^-6 T   or 1.4 uT

DIrection is out of the page