(a)[2]
Explain why the proton’s route in the magnetic field is an arc of a circle.
(b)[4]
The proton’s angular speed in the magnetic field is $\omega$. Derive an expression for $\omega$ in terms of $B$, $q$ and $m$.
Physics 9702 · AS & A Level · Force on a moving charge
Force on a moving charge — practice question
A proton with mass $m$ and charge $+q$ moves in a vacuum along a straight path at speed $v$. It then enters a region where the magnetic flux density is uniform and has magnitude $B$, as shown in Fig. 4.1. The magnetic field is at right angles to the proton’s direction of travel.
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