Tiny sensors in smartphone could be used to determine the position of the phone on the Earth’s surface by measuring the Earth’s magnetic field. A current I is applied to a

slice of semiconductor as shown in Figure 1(a).

After detecting magnetic field, Bexternal of 2.55 mT on the slice, the electrons collect at

the top edge of the slice and the bottom edge becomes positively charged as shown in

Figure 1(b).

(a) Explain why the electrons collect at the top of the edge of the slice.

(b) Determine the magnitude of the maximum magnetic force that could be exerted on

the electron if the electron moves through the field with a speed of 5.5 × 106 m s

−1

.

(c) What is the magnitude of the maximum acceleration of the electron?

(d) Would the field exert the same magnetic force exerted on a proton moving through

the field with the same speed in (c)? Explain your answer.

(e) If there is a straight wire with current of 6.0 A placed 1.5 mm near the slice of

semiconductor as shown in Figure 1(c), determine the magnitude and direction of the

magnetic field at point A.