Which method can be used to distinguish between the two types of carriers?

a) Hall effect

b) Rayleigh method

c) Doppler effect

d) Fermi effect

2. Find the resistance of an intrinsic Ge rod cm long, 1mm wide and 1mm thick at 300K.

a) 2.32 ohm

b) 5314 ohm

c) 4310 ohm

d) 431 ohm

3. A semiconducting crystal 12mm long, 5mm wide and 1mm thick has a magnetic flux density of 0.5Wb/m2applied from front to back perpendicular to largest faces. When a current of 20mA flows length wise through the specimen, the voltage measured across its width is found to be 37V. What is the Hall coefficient of this semiconductor?

a) 3710-6m3/C

b) 3.710-6m3/C

c) 3.7106m3/C

d) 0

4. The intrinsic carrier density at room temperature in Ge is 2.371019/m3. If the electron and hole mobilities are 0.38 and 0.18 m2/Vs respectively. Calculate its resistivity.

a) 0.18ohm m

b) 0.460ohm m

c) 0.4587ohm m

d) 0.709ohm m

5. A silicon plate of thickness 1mm, breadth 10mm and length 100mm is placed in a magnetic field of 0.5 Wb/m2acting perpendicular to its thickness. If 10-3A current flows along its length, calculate the Hall voltage developed, if the Hall coefficient is 3.66104m3/Coulomb.

a) 1.8310-3Volts

b) 3.6610-4Volts

c) 0.5 Volts

d) 25.150 Volts

6. The conductivity of germanium at 20C is 2/ohm m. What is its conductivity at 40C? Eg=0.72eV

a) 1.3810-23/Ohm m

b) 1.0002/Ohm m

c) 293/Ohm m

d) 313/Ohm m

7. What is the Fermi energy of a n-type semiconductor?

a) E

b) E(F)= (Ec+ Ev)/2

c) EF= (Ec+ Ed)/2

d) EF= (Ev+ Ea)/2

8. EF= (Ec+ Ev)/2, this represents the Fermi energy level of which of the following?

a) Extrinsic semiconductor

b) N-type semiconductor

c) P-type semiconductor

d) Intrinsic semiconductor

9. For semiconductors, the resistivity is inversely proportional to the temperature for semiconducting materials.

a) True

b) False