Answer to Question #303021 in Electricity and Magnetism for mika

Question

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

Answer 1

$B_{max}=B\frac{mg}{ev}=6.77~mT.$