Under what specific condition is the magnetic force exerted on a charged particle zero?

Answer

When the velocity is perfectly parallel or antiparallel to the magnetic field lines.

Because the magnetic force calculation involves the sine of the angle between velocity and field, when this angle is zero degrees (parallel) or 180 degrees (antiparallel), the sine evaluates to zero, resulting in zero magnetic force.

Under what specific condition is the magnetic force exerted on a charged particle zero?
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