A particle of mass m, charge Q and kinetic energy T enters a uniform transverse magnetic field B. After 3 s, what will be its kinetic energy?
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A particle of mass m, charge Q and kinetic energy T enters a uniform transverse magnetic field B. After 3 s, what will be its kinetic energy?

G1 Physics · Accepted Answer

Step 1: Magnetic force F⃗ = q(v⃗ × B⃗) is perpendicular to the instantaneous velocity. Step 2: Power delivered by the magnetic force is P = F⃗·v⃗ = 0. Step 3: The work–energy theorem gives ΔK = W(B) = 0, so kinetic energy cannot change. Final answer: (C) T.