**Exercise 19.38**

Part A = 0 T

Part B = 4.0*10^-6

**Solutions Below:**

Two long, parallel wires separated by 60 cm each carry currents of 3.0 A in a horizontal direction.

Part A

Find the magnetic field midway between the wires if the currents are in the same direction.

Express your answer using two significant figures.

Express your answer using two significant figures.

Since the currents are in opposite directions, the magnetic field between the wires is canceled out and is zero. Just use the right hand rule.

0 T

Part B

Find if they are in opposite directions.

Express your answer using two significant figures.

Express your answer using two significant figures.

The magnetic field from each wire is:

B = μ_{0} * i / (2πr)

μ_{0} is the magnetic constant and = 1.2566 * 10^-6 m * kg / s^{2}

B = 1.2566 * 10^-6 * 3.0 / (2 * 3.14159 * 0.30)

B = 2.0 * 10^-6

Since there are two wires, multiply the field from each wire by 2:

4.0*10^-6