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The two wires shown in the figure below are separated by d = 10.4 cm and carry c

ID: 1441430 • Letter: T

Question

The two wires shown in the figure below are separated by d = 10.4 cm and carry currents of I = 5.15 A in opposite directions.

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

_________T

(b) Find the magnitude and direction of the net magnetic field at point P1, 10.4 cm to the right of the wire on the right. magnitude

_________T

(c) Find the magnitude and direction of the net magnetic field at point P2, 2d = 20.8 cm to the left of the wire on the left. magnitude

_________T

Explanation / Answer

The formula for find the magnetic field from a current carrying wire is...

B = oI/2r

That will provide magnitude. The right hand rule will determine direction.

(a)

The right hand rule shows that both wires will produce a magnetic field into the page at a point midway between them, so the two magnetic fields will add to give the value

B = oI/2r + oI/2r

B = (4 X 10-7)(5.15)/(2)(.052) + (4 X 10-7)(5.15)/(2)(.052)

B = 3.96 X 10-5 T

  35.4 T directed into the page

(b)

The field from the closer wire will point out of the page, and the field from the farther wire will point into the page. The net will subtract where the field from the closer wire will be stronger.

B = oI/2r - oI/2r

B = (4 X 10-7)(5.15)/(2)(.104) - (4 X 10-7)(5.15)/(2)(.208)

B = 4.95 X 10-6 T   

4.95 T directed out of the page

(c)

The field from the closer wire will point out of the page, and the field from the farther wire will point into the page. The net will subtract where the field from the closer wire will be stronger.

B = oI/2r - oI/2r

B = (4 X 10-7)(5.15)/(2)(.208) - (4 X 10-7)(5.15)/(2)(.312)

B = 1.65 X 10-6 T

1.65 T directed out of the page