1. Conductivity depends on: a. The number of mobile charge carriers per unit vol

Question

1. Conductivity depends on:

a. The number of mobile charge carriers per unit volume (N with units of m-3 )2

b. Charge per carrier, q (units of C)

c. The mobility of the charge,, with units m2 /(V-s)

d. All

2. The conduction band is defined as:

a. The highest energy band that is at least partially occupied

b. All bands below the valence band

c. The energy band above the valence band

d. the magnitude of the forbidden energy range between the valence and conduction bands

3. As the temperature increases the electrical conductivity of a conductor:

a. Increases

b. Decreases

c. Stays the same over the entire temperature range d. None of the above

4. What are the main charge carriers that can occur in materials?

a. Electrons & holes

b. Electrons & holes & photons

c. Electrons & holes & excitons

d. Electrons & hole & ions

5. Insulators are usually made of atoms that form

a. strong ionic (partially covalent) bonding

b. metallic bonds

c. a mix of ionic and metallic bonding

d. none of the above

6. How does work hardening affect the electrical conduction of cupper?

a. It increases it

b. It decreases it

c. It does not affect the conduction

d. None of the above

7. What type of electronic orbitals is shown on the right?

a. s-type orbitals

b. f-type orbitals

c. d-type orbitals

d. p-type orbitals

8. As the temperature increases the electrical conductivity of an extrinsic (i.e. doped) semiconductor:

a. Increases

b. Decreases

c. Stays the same over the entire temperature range

d. None of the above

9. ‘Plastic’ semiconductors are made more processable by:

a. crosslinking them

b. introducing double bonds

c. introducing side chains

d. introducing end groups

10. The resistance to flow of current of a material depends on the intrinsic resistivity, the length and the crossectional area of an object as:

a. R = (La)

b. R = (/L)a

c. R = (L/a)

d. R = (/L)/a

11. In an intrinsic semiconductor the amount of free electrons:

a. Increases linearly with temperature

b. Increases exponentially with temperature

c. Does not increase with temperature

d. Decreases linearly with temperature

e. Decreases exponentially with temperature

12. In organic materials the conduction band is defined as:

a. The HOMO

b. The LUMO

c. The COMO

d. The VOMO

13. In an extrinsic p-type semiconductor:

a. the number of free electrons n = the number of holes p

b. n << p

c. p << n

d. none of the above

14. In metals, electrons are:

a. Localized

b. Delocalized

c. Trapped

d. None of the above

15. In a real solid, the electrons scatter:

a. collisions with imperfections

b. traps

c. collisions with atomic thermal vibrations

d. A and B

e. A and C

f. A, B, C

16. Which of the following statements is correct:

a. Electrons and holes move in the same direction

b. Electrons and holes move in opposite direction

c. The way the move depends on the situation

d. None of the above

17. Organic semiconductors:

a. are based on saturated molecules

b. are based on materials that contain no single bonds

c. are conjugated materials

d. None of the above

18. What is a good n-dopant for Si:

a. Carbon

b. Phosphor

c. Germanium

d. Aluminium

e. All of the above

19. For an extrinsic semiconductor, at high temperatures:

a. all carriers are due to the extrinsic excitations

b. most dopants are ionized (saturation region)

c. intrinsic generation of carriers dominates

d. all of the above e. none of the above

20. The conductivity range that polymeric materials cover is:

a. One order of magnitude

b. About two orders of magnitude

c. About 20 orders of magnitude

d. About 100 orders of magnitude

1. Conductivity depends on: a. The number of mobile charge carriers per unit volume (N with units of m 3)2 b. Charge per carrier, q (units of C) c. The mobility of the charge u, with units m2/(V-s) d. All 2. The conduction band is defined as: a. The highest energy band that is at least partially occupied b. All bands below the valence band c. The energy band above the valence band d. the magnitude of the forbidden energy range between the valence and conduction bands 3. As the temperature increases the electrical conductivity of a conductor: a. Increases b. Decreases c. Stays the same over the entire temperature range d. None of the above 4. What are the main charge carriers that can occur in materials? a. Electrons & holes b. Electrons & holes & photons c. Electrons & holes & excitons d. Electrons & hole & ions 5. Insulators are usually made of atoms that form a. strong ionic (partially covalent) bonding b. metallic bonds c. a mix of ionic and metallic bonding d. none of the above 6. How does work hardening affect the electrical conduction of cupper? a. t increases it b. t decreases it c. It does not affect the conduction d. None of the above

Explanation / Answer

1) The correct answer is The number of mobile charge carriers per unit volume (N with units of m-3 )2

Conductivity is the property to conduct or measure of its ability to conduct electricity.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.