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Question
An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because ______.
Options
the two magnetic forces are equal and opposite, so they produce no net effect.
the magnetic forces do no work on each particle.
the magnetic forces do equal and opposite (but non-zero) work on each particle.
the magenetic forces are necessarily negligible.
Solution
An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because the magnetic forces do no work on each particle.
Explanation:
The work-energy theorem states that net work done equals final kinetic energy - the initial kinetic energy of the item.
The following equation demonstrates the relationship between work and kinetic energy:
∑W = K2 – K1v
As the electron and proton move under the influence of mutual interactions, the magnetic forces will be perpendicular to their motion, acting as a centripetal force for the particle.
As a result of performing the uniform circular motion in this manner, the particle's speed remains constant.
As a result, the particle's kinetic energy remains unchanged.
As a result, these forces perform no work.
`vecF_m = q(vecv xx vecB) * F_m` (magnetic force) will be perpendicular to both B and v, where B represents the external magnetic field and v represents particle velocity.
That is why the magnetic pull of one particle on another is ignored.
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