A flat ribbon (strip) of silver having a thickness (t = 0.2 mm) is used in a Hall effect measurement of uniform magnetic field perpendicular to the ribbon, as shown in the Figure. The Hall coefficient for silver is (RH = 0.84 x 10-10m3/c). (a) What is the density of charge carriers in silver? (b) If a current (I = 20 A) %3D %3D produces a Hall voltage (VH = 15 µV), what is the magnitude of the applied magnetic field? Solution

Arefrigerator uses r-134a as the working fluid and operates on the ideal vapor-compression refrigeration cycle except for the compression process. the refrigerant enters the evaporator at 120 kpa with a quality of 34 percent and leaves the compressor at 70°c. if the compressor consumes 450 w of power, determine (a) the mass flow rate of the refrigerant, (b) the condenser pressure, and (c) the cop of the refrigerator. (0.00644 kg/s, 800 kpa, 2.03)