Magnetic Forces Between Wires
Attraction and repulsion produced by currents in parallel conductors
|
This
movie is part of the collection:
Show Me The Physics
E) Forces between current carrying wires
| Onsite |
Opposite Currents
Wires repel
Same Current Direction?
Wires Attract
Wires, perpendicular F = 0
| S.M.U. Physics | | Onsite |
|
|
Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. Two parallel wires carry currents in the SAME direction. The wires:
2. Two parallel wires carry currents in OPPOSITE directions. The wires:
3. Two current-carrying wires cross each other at a right angle (perpendicular). The magnetic force between them is:
4. Two parallel wires with same-direction currents are attracting. The current in ONE wire is reversed. Now the wires:
5. Why do two current-carrying wires exert forces on each other at all?
Two Parallel Wires
Two long, straight, parallel wires are a short distance apart. Each produces a magnetic field that acts on the current in the other wire.
When the currents in the two wires are in the same direction, what happens?
▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)
Challenge score: 0 / 6
C1. Each wire’s magnetic field is proportional to its current, and the force on a current in a field is F = BIL. Place a check mark in three boxes to indicate the changes that would increase the force between the wires.
C2. One current is reversed. What happens now?
C3. A student makes the following claim.
Place a check mark in either the Support or Refute box. Justify your response.
C4. Wire 1 is on the left and wire 2 is on the right, with currents in the same direction. A sensor shows that wire 1 exerts a force of 0.30 mN on wire 2. The currents in both wires are then doubled, keeping their directions. Choose the direction of the new force on wire 2, and determine its magnitude.
●
C5. How does the force wire 1 exerts on wire 2 compare with the force wire 2 exerts on wire 1, if wire 1 carries more current?
C6. In a power cord, the two wires carry equal currents in opposite directions and are placed very close together. Identify one benefit of this arrangement and one risk that engineers must design for.