A horizontal wire carries a large current. A second wire carrying a current in the same direction is suspended below it.Can the current in the upper wire hold the lower wire in suspension against gravity?
http://physics.bu.edu/~duffy/semester2/c14_forcewires.html
Thanks. Therefore, I think the answer is "yes". Am I right? Anyway, another question is that, under what condition will the lower wire be in equilibrium?
Yes, the current in the upper wire can hold the lower wire in suspension against gravity.
When a current flows through a wire, it creates a magnetic field around the wire. The magnetic field exerts a force on any nearby conductor carrying a current. According to Ampere's law, the force between two parallel conductors carrying currents in the same direction is attractive, meaning they are pulled towards each other.
In this scenario, the current in the upper wire creates a magnetic field around it. The lower wire, carrying a current in the same direction, will experience an upward force due to the magnetic field induced by the upper wire. This upward magnetic force can counteract the gravitational force acting on the lower wire and keep it suspended.
It is important to note that the ability to suspend the lower wire against gravity depends on the magnitude of the current in the upper wire. If the current is not sufficiently strong, it may not be able to overcome the gravitational force and hold the lower wire in suspension.
To determine if the current in the upper wire can hold the lower wire in suspension against gravity, we need to understand the relationship between the current and the magnetic field it creates.
When a current flows through a wire, it generates a magnetic field around it, following a pattern known as the right-hand rule. The magnetic field lines form concentric circles around the wire, with the direction determined by the direction of the current.
Considering the scenario you described, the magnetic field generated by the upper wire will intersect with the lower wire. This interaction between the two magnetic fields can lead to a force between the wires, known as the magnetic force.
The magnetic force between two parallel current-carrying wires can be attractive or repulsive, depending on the direction of the currents. When the currents flow in the same direction, the wires will experience an attractive force, and if the currents flow in opposite directions, the force will be repulsive.
In our case, since the currents in both wires are in the same direction, an attractive force will be exerted. This force can counteract the force of gravity and potentially hold the lower wire in suspension if it is strong enough.
However, the strength of the magnetic force depends on several factors, such as the magnitude of the currents, the distance between the wires, and other magnetic properties. Therefore, to determine if the current in the upper wire can hold the lower wire in suspension against gravity, we need additional information about the specific values of these factors.
In summary, it is possible for the current in the upper wire to hold the lower wire in suspension against gravity if the attractive magnetic force is strong enough. The exact determination of whether it can or cannot be done requires more specific details about the scenario.