PH8252-PIS MCQ TEST(30.1.20)

1. According to classical free electron theory, metal consists of

• a) Free electrons

• b) Tightly bound electrons

• c) Neither free electrons nor tightly bound electrons

• d) None of the above

1. Mean free path is defined as the

• a) Product of velocity and collision time

• b) Ratio between velocity and collision time

• c) Sum of relaxation time and velocity

• d) Difference between velocity and collision time

3. Fermi distribution function is

• a) distribution of electrons with respect to temperature

• b) distribution of atoms with respect to temperature

• c) distribution of temperature among various energy levels

• d) All of the above

4. Which of the following have large forbidden energy gap?

• a) Semiconductors

• b) Conductors

• c) Insulators

• d) Both a and b

5. The mass acquired by electron when it is accelerated in a periodic potential is

• a) Reduced mass

• b) Effective mass

• c) Whole mass

• d) None of the above

6. At high temperature, the electron loses their quantum mechanical behaviour, then

• a) Fermi function remains invariant

• b) Fermi function reduced to Boltzmann function

• c) Boltzmann function changes to Fermi function

• d) None of the above

7. The semiconductors have an empty conduction band at a temperature of

• a) 10 K

• b) 100K

• c) 0K

• d) 20K

8. Compound semiconductors are made of combination of

• a) 4^th and 5^th group elements

• b) 3^rd and 5^th group elements

• c) 2^nd and 6^th group elements

• d) Both b and c

• e) Both a and b

9. Intrinsic semiconductors are semiconductor in

• a) doped form

• b) pure form

• c) lightly doped form

10. Intrinsic Carrier concentration is defined as the

• a) No of electrons per unit volume in conduction band

• b) No of holes per unit volume in valence band

• c) Both a and b

• d) None of the above