Physics 9702 · AS & A Level · Force on a moving charge
Force on a moving charge — practice question
Positively charged particles move through a vacuum, passing via three narrow slits $S_1$, $S_2$, and $S_3$, as illustrated in Fig. 5.1. Each particle travels with speed $v$ and carries charge $q$. In the space between slits $S_2$ and $S_3$, there is a uniform magnetic field of flux density $B$ together with a uniform electric field of field strength $E$.
(a(i))[1]
State the equation for the force $F$ on a charged particle caused by the magnetic field.
(a(ii))[1]
State the equation for the force $F$ on a charged particle caused by the electric field.
(b)[2]
The electric field is directed downward in the plane of the paper, as shown in Fig. 5.1. State and explain the direction of the magnetic field so that the positively charged particles can travel undeviated through the region between slits $S_2$ and $S_3$.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$Bqv\sin\theta$ or $Bqv\cos\theta$” …