Consider a piece of an n-type semiconductor 15 cm long. 0.7 cm wide, and 1.5 mm (hick. If we apply a 0.35 V voltage across the length, we find that the material conducts a current of 15 mA. If we then put it in a magnetic Held of 1.2 Tesla parallel to the thickness, we find that the Hall voltage across the width is 3 mV.

1. Calculate the mobility of the carriers and the electron concentration in the conduction band.

2. Assuming that the effective mass of the carriers coincides with the electron mass at rest, estimate the cyclotron resonance frequency in this magnetic field and the wavelength of the respective electromagnetic radiation. Is this magnetic field sufficiently large to actually observe the cyclotron resonance?