Two long, straight, parallel wires carry currents in the same direction. What is the direction of the magnetic field produced by wire $2$ at the location of wire $1$?

• A. To the right
• B. To the left
• C. Out of the page
• D. Into the page

Answer: (D)

Verified step by step guidance

1. Identify the direction of the current in wire 2. Since both wires carry currents in the same direction, assume the current in wire 2 is upward (for example).
2. Recall the right-hand rule for magnetic fields around a current-carrying wire: Point your right thumb in the direction of the current, and your fingers curl in the direction of the magnetic field.
3. Apply the right-hand rule to wire 2: With your thumb pointing upward (direction of current), your fingers curl around the wire. At the position of wire 1 (which is parallel and next to wire 2), determine the direction of the magnetic field.
4. Since wire 1 is to the left or right of wire 2, the magnetic field at wire 1 due to wire 2 will be either into or out of the page. Using the right-hand rule, the magnetic field at wire 1 is directed into the page.
5. Conclude that the magnetic field produced by wire 2 at the location of wire 1 points into the page.