Physics 9702 · AS & A Level · Force on a moving charge
Force on a moving charge — practice question
Positively charged particles move in a vacuum through three narrow slits $S_1$, $S_2$ and $S_3$, as illustrated in Fig. 5.1. Each particle travels at speed $v$ and carries charge $q$. A uniform magnetic field of flux density $B$ and a uniform electric field of field strength $E$ occupy the region between slits $S_2$ and $S_3$.
(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 acts downward in the plane of the paper, as shown in Fig. 5.1. State and explain which way the magnetic field should point so that the positively charged particles can pass 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 $Bqv\cos\theta$” …