 Solution

ID: past-exam-of-the-physics-2-paper-of-the-university-of-oxford/2013-resit/1/ii/solution

\frac{d W}{d t} = F \cdot v = q (v \times B) \cdot v = 0.

Therefore

W = 0

over any part of the orbit. The magnetic force changes direction of motion but leaves the speed and kinetic energy constant.

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