Consider an XY coordinate plane. Wire A is placed along the y-axis at x=0 and wi
ID: 1908618 • Letter: C
Question
Consider an XY coordinate plane. Wire A is placed along the y-axis at x=0 and wire B is placed parallel to wire A at x= 26 cm. Wire A has a current of 1.7 A in the positive y-direction and wire B has a current of 3.9 A in the negative y-direction. (a) Find the magnitude and direction of the magnetic field at x=13 cm. (b) Find the magnitude and direction of the magnetic field at x = 47 cm (c) Find the force per unit length between the two wires. Is it attractive or repulsive? Answers: (a) Magnitude of magnetic field (in ?T): Direction (1: positive x direction, 2: negative x direction, 3: positive y direction, 4: negative y direction, 5: into the paper, 6: out of the paper): (b) Magnitude of magnetic field (in ?T): Direction (1: positive x direction, 2: negative x direction, 3: positive y direction, 4: negative y direction, 5: into the paper, 6: out of the paper): (c) Force per length (in ?N/m): Attractive or repulsive (1 for attractive, 2 for repulsive):Explanation / Answer
B field from each wire is B = k I / r
so
(a) from wire A: B = .2 * 1.7 / 0.13 = 2.6154 uT into the page
from wire B: B = .2 * 3.9 / 0.13 = 6.00 uT into the page
magnitude of B field at x = 13 cm is 8.6154 uT into the paper
(b)
from wire A: B = .2 * 1.7 / 0.47 = 0.7234 uT into the page
from wire B: B = .2 * 3.9 / 0.21 = 3.7143 uT out of the page
magnitude of B field at x = 47 cm is 2.99 uT out of the paper
(c) force per length is
F/L = k I I / r = 0.2 * 1.7 * 3.9 / 0.26 = 5.10 uN/m repulsive