Railgun magnetic force does no work?Q1) The Lorentz magnetic force on a moving electron is always perpendicular to its motion; so no work is done. Yet, why is work done in railgun operation.Q2) For every action, there must always be a reaction. The recoil force of the railgun will be transmitted to the structure holding the rails. But what is the actual mechanism that transfers the force of reaction?

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Elliana Shelton · Accepted Answer

Regarding your first question, in situations like this where it looks like the magnetic component of the Lorentz force might be doing work, what is usually happening is there is an electric field somewhere that is &quot;mediating&quot; the energy transfer. Here is how it works in this case. Suppose the projectile is in motion and being accelerated.1.A current is being made to flow through the projectile. Positive charges have a velocity component in the same direction, as well as a velocity component in the direction of motion of the projectile.2.Because of the motion of the projectile, there is a component of magnetic Lorentz force on positive charges in the direction that opposes current flow.3.An electric field in the direction of the current is induced in the projectile, to counteract this force.4.Since positive charges have a velocity component in the direction of current flow and the electric Lorentz force is also in that direction, it is this force that is responsible for energy transfer to charges.

Flakqfqbq · Accepted Answer

Q1)&quot;Lorentz force does not work&quot; is true only for magnetic force acting on a single point charged particle.Macroscopic magnetic force acting on current-carrying bodies like wires may do work. It is a different kind of force than the Lorentz force in the first statement is; it is a result of all forces, external and internal, acting on the projectile.Q2) In EM theory Newton&#039;s 3rd law does not hold in general, only in special circumstances it does. In railgun there is a recoil, but there is no &quot;mechanism&quot; - it is due to ponderomotive EM forces (EM forces acting on matter) acting back on the parts of the gun.

Railgun magnetic force does no work? Q1) The Lorentz magnetic force on a moving electron is always

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