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DI Question 10 pts Two long, straight wires are perpendicular to the plane of th

ID: 1864526 • Letter: D

Question

DI Question 10 pts Two long, straight wires are perpendicular to the plane of the paper and at a distance 0.2 m from each other, as shown in the figure. The wires carry currents of 11-1 A and 12-4.6 A in the direction indicated (out of the page). Find the magnitude and direction of the magnetic field (in uT) at a point A midway between the wires. You need to indicate the direction with a positive or a negative value for the magnetic ield Keep in mind that a vector is positive if directed to the right and negative if directed to the left on the x axis and it is positive if directed up and negative if directed down on the y axis Your answer should be a number with two decimal places, do not include the unit.

Explanation / Answer

using the right hand rule, the field from left wire point up at point A and field from right wire points down at A.

We know that magnetic field at a distance 'r' from a current carrying wire is given as

B = uoI / 2*pi*r

From left wire,

Bleft = 4*pi*10-7*1 / 2*pi*0.1

Bleft = 2e-6 T or 2 uT

From right wire,

Bright = -4*pi*10-7*4.6 / 2*pi*0.1

Bright = -9.2e-6 T or -9.2 uT

Net B at point A

BA = -9.2 uT + 2 uT

BA = - 7.2 uT

Negative sign tells that field points downward