Physics 9702 · AS & A Level · Force on a moving charge
Force on a moving charge — practice question
As shown in Fig. 9.1, a thin slab of conducting material has faces PQRS and VWXY set at right angles to a uniform magnetic field of flux density $B$. Electrons enter the slab perpendicular to face SRXY. A potential difference, called the Hall voltage $V_H$, forms across two faces of the slab.
(a(i))[1]
Use the letters in Fig. 9.1 to identify the two faces across which the Hall voltage is formed.
(a(ii))[2]
State and explain which of the two faces named in a(i) is the more positive one.
(b(i))[1]
The Hall voltage $V_H$ is represented by $V_H = \frac{BI}{ntq}$. Use the letters in Fig. 9.1 to identify the distance $t$.
(b(ii))[1]
State what the symbol $n$ means.
(b(iii))[2]
State and explain the effect, if any, on the polarity of the Hall voltage when negative charge carriers (electrons) are replaced by positive charge carriers moving in the same direction towards the slice.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “The correct faces are PSYV and QRXW” …