Question 1
A very long thin wire produces a magnetic field of

at a distance of

from the wire. What is the magnitude of the current? (
μ0 = 4π × 10
-7 T ∙ m/A)
◦ 1.0 mA
◦ 3100 mA
◦ 4000 mA
◦ 2.0 mA
Question 2
Three very long, straight, parallel wires each carry currents of 4.0 A, directed out of the page as shown in the figure. These wires pass through the vertices of a right isosceles triangle as shown. Assume that all the quantities shown in the figure are accurate to two significant figures. What is the magnitude of the magnetic field at point P at the midpoint of the hypotenuse of the triangle? (
μ0 = 4π × 10
-7 T ∙ m/A)

◦ 4.4 µT
◦ 57 µT
◦ 1.8 µT
◦ 18 µT
◦ 130 µT