Electronics – LearnITbyTests

1. Which of the following statements is CORRECT about semiconductors?

They have an almost completely filled valance band and a conduction band which has almost no electron and are separated by a very small forbidden energy gap.

An increase in temperature increases the chance of an electron moving from the valence band to conduction band thus enabling electrical conductivity.

Total current flow in semi-conductors is therefore due to the flow of electrons and holes.

All of the above

Question 1 of 25

2. An impure semi-conductor is called?

Intrinsic semi-conductor

Extrinsic semi-conductor

Bi-polar semi-conductor

None

Question 2 of 25

3. Which of the following is an example of a pure semi-conductor?

Silicon

Germanium

Boron

diamond

Question 3 of 25

4. The N-type semi-conductor is formed by?

Doping an intrinsic semi-conductor with trivalent atoms

Doping an intrinsic semi-conductor with pentavalent atoms

Doping an intrinsic semi-conductor with quadravalent atoms

Doping an intrinsic semi-conductor with sugar or cocaine

Question 4 of 25

5. Which of the following statement is INCORRECT about the P-type semi-conductor?

It is formed by doping trivalent atoms into intrinsic semi-conductors

It is formed by doping intrinsic semiconductors with atoms with 5 valence electrons

The electrons are the minority charge carriers

The holes are the majority charge carriers

Question 5 of 25

6. Define Rectification

Transforming an alternating voltage into a direct voltage

Transforming an alternating current into a direct current

Transforming an alternating voltage into a unidirectional voltage

All of the above

Question 6 of 25

7. Why is the impurity element in the N-type semi-conductor referred to be having Donor atoms?

Its atoms have five electrons, four of which participate in forming a covalence bond and the fifth which is donated for electrical conductivity.

Because it it formed by doping pentavalent atom with extrinsic semi-conductor

Because it is formed by donated atoms.

None

Question 7 of 25

8. Which of the following statements is CORRECT about N-type semi-conductors?

It is formed by a donor atom and a pure semi- conductor

The electrons are the majority charge carriers

The holes are the minority charge carriers

All of the above

Question 8 of 25

9. The electrical resistance of semi-conductors reduces with an increase in temperature. True or False?

False

True

Maybe

None

Question 9 of 25

10. Mention the 2 types of Rectification

Half wave

Full-moon

Full wave

half moon

Question 10 of 25

11. In a P-N junction when the P type region is connected to the negative and the N-type region to the positive terminal of an external cell or battery. It is said to be:

Reverse biased

Forward biased

Left biased

Right biased

Question 11 of 25

12. Doping is the act of adding small quantities of impurities to a pure semi-conductor to enhance its conductivity. True or False?

False

True

Maybe

None

Question 12 of 25

13. Which of the following statements is CORRECT about Intrinsic semi-conductors?

It is an extremely pure semi-conductor

At room temperature it becomes a poor conductor but its conductivity increases as temperature increases.

The no. of electrons equals to the no. of holes

All of the above

Question 13 of 25

14. In a P-N junction when the P type region is connected to the positive and the N-type region to the negative terminal of an external cell or battery. It is said to be:

Reverse biased

Forward biased

Left biased

Right biased

Question 14 of 25

15. Which of the following statement is INCORRECT about conductors?

In conductors the valence and conduction bands largely overlap

Electrons move freely from the partly filled valence band to the conduction band

An increase in temperature increases the overlap and hence lowers the electrical resistance of conductors

An increase in temperature increases the vibrations of the atoms and interferes with electron flow hence the resistance increases.

Question 15 of 25

16. A pure semi-conductor is called?

Extrinsic semi-conductor

Intrinsic semi-conductor

Bi-polar semi-conductor

None

Question 16 of 25

17. The flow of current in conductors is by movement of electrons. True or False?

False

True

Maybe

None

Question 17 of 25

18. Which of the following statements is INCORRECT about reverse biasing?

The N-type region of P-N junction is connected to the positive terminal and the P-type region connected to the negative terminal of a cell/battery.

When the switch is ON, a reverse current flows which increases the potential barrier and depletion layer in the P-N junction.

A small current flows in the circuit due to flow of minority charge carriers.

A large amount of current flows in the circuit due to majority charge carriers

Question 18 of 25

19. State the energy band theory

When 2 or more atoms are brought far from each other, the energy levels splits

When 2 or more atoms are brought closer to each other their energy level split into smaller energy levels called bands.

When 2 or more atoms are brought closer to each other they form bands

None

Question 19 of 25

20. Which of the following statement is CORRECT about insulators?

Insulators have extremely high resistance to flow of electric current

They consist of 2 bands: a valence band and an empty conductor band which are separated by a very large forbidden energy gap.

Temperature increase or addition of impurities to insulators has no effect on their conductivity.

All of the above

Question 20 of 25

21. Mention the most important bands in electronics

Valence band

Conduction band

induction band

Radiation band

Question 21 of 25

22. The energy gap between the conduction and valence bands is called?

The forbidden energy gap

Insulators

Conductors

Semi-conductors

Question 22 of 25

23. Which of the following statements is CORRECT about forward biasing?

The P-type region of P-N junction is connected to the positive terminal and the N-type region connected to the negative terminal of a cell/battery.

When the switch is ON, current flows to reduce the potential barrier and depletion layer in the P-N junction.

A large forward current is allowed to flow in the circuit

All of the above

Question 23 of 25

24. The region occupied by the uncovered fixed ion in P-N junction is called?

Forbidden energy gap

Depletion layer

Acceptor atom

Donor atom

Question 24 of 25

25. Mention the 2 types of extrinsic semi-conductors

N-type

P-type

W type

Z-type

Question 25 of 25

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