Electronics Sheet (1)

[YoussefLasheen]

1. An atom consist of:

A. one nucleus and only one
electron
B. one nucleus and one or
more electrons
C. protons, electrons, and
neutrons
D. answer b or c

2. The atomic number of silicon is:

A. 8
B. 14
C. 4

3. The atomic number of germanium is:

A. 32
B. 4
C. 8

4.The most widely used semiconductive material in electronic device is:

A. silicon
B. carbon
C. germanium
D. copper

5. The energy band in which free electrons exist is the:

A. first band
B. conduction band
C. second band
D. valence band

6. Electron-holes pairs are produced by:

A. ionization
B. thermal energy
C. recombination
D. doping

7. Recombination is when:

A. a crystal is formed
B. a positive and a negative
ion bond together
C. an electron falls into a
hole
D. a valence electron
becomes a conduction
electron

8. Each atom in a silicon crystal has:

A. no valence electrons
because all are shared
with others atoms
B. eight valence electrons
because all are with other
atoms
C. four valence electrons
D. four conduction electrons

9. The current in a semiconductor is produced by:

A. holes only
B. electrons only
C. both electrons and holes
D. negative ions

10. In an intrinsic semiconductor:

A. there are no free
electrons
B. the free electrons are
thermally produced
C. there are only holes
D. there are as many
electrons as there are
holes
E. answer b and d

11. A pure semiconductor behaves like an insulator at 00 K because:

A. There is no
recombination of
electrons with holes
B. Drift velocity of free
electrons is very small
C. Free electrons are not
available for current
conduction
D. Energy possessed by
electrons at that low
temperature is almost
zero

12. In semiconductor the forbidden energy gap lies:

A. Just below the
conduction band
B. Just above the
conduction band
C. Either above or below
the conduction band
D. Between the valence
band and conduction
band

13. A semiconductor is formed by ……… bonds.

A. Covalent
B. Electrovalent
C. Co-ordinate
D. None of the above

14. The process of adding an impurity to an intrinsic semiconductor is called:

A. atomic modification
B. doping
C. recombination
D. ionization

15. A trivalent impurity is added to silicon to create:

A. germanium
B. an n-type semiconductor
C. a depletion region
D. a p-type semiconductor

16. When diode is forward-biased:

A. the only current is hole
current
B. the only current is
produced by majority
carriers
C. the current is produced
by both holes and
electrons
D. the only
current is electron current

17. The purpose of a pentavalent impurity is to:

A. increase the number of
free electrons
B. create minority carriers
C. reduce the conductivity
of silicon
D. increase the number of
holes

18. Holes in an n-type semiconductor are:

A. minority carriers that are
thermally produced
B. majority carriers that are
thermally produced
C. minority carriers that are
produced by doping
D. majority carriers that are
produced by doping

19. A pn junction is formed by:

A. ionization
B. the boundary of a p-type
and an n-type material
C. the recombination of
electrons and holes
D. the collision of a proton
and a neutron

20. The depletion region consists of:

A. nothing but minority
carriers
B. positive and negative
ions
C. no majority carriers
D. answer b and c

21. In a PN junction with no external voltage, the electric field between acceptor and donor ions is called:

A. Peak
B. Barrier
C. Threshold
D. Path

22. For a PN junction diode, the current in reverse bias may be:

A. Few miliamperes
B. Between 0.2 A and 15 A
C. Few amperes
D. Few micro or nano
amperes

23. In a PN junction when the applied voltage overcomes the ........ potential, the diode current is large, which is known as .............

A. Depletion, negative bias
B. Reverse, reverse bias
C. Resistance, reverse bias
D. Barrier, forward bias

24. The term bias means:

A. a dc voltage is applied to
control the operation of a
device
B. neither a, b nor c
C. the ratio of majority
carriers to minority
carriers
D. the amount of current across a diode

25. In a reverse biased PN junction the current through the junction increases abruptly at:

A. 0.5 V
B. 1.1 V
C. 0.72 V
D. Breakdown voltage

26. Although current is blocked in reverse bias:

A. there is some current due
to majority carriers
B. there is very small
current due to minority carriers
C. there is an avalanche current

27. When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to:

A. the diode barrier
potential
B. the bias battery voltage
C. the total
D. circuit voltage
E. 0 V

28. At room temperature N-type material will have....

A. More of electrons
B. More of holes
C. Equal number of electrons and holes

29. A forward biased pn junction diode has a resistance of the order of:

A. Ω
B. kΩ
C. MΩ
D. None of the above

30. A reverse biased pn junction has resistance of the order of:

A. Ω
B. kΩ
C. MΩ

[YoussefLasheen]

1. D
2. B
3. A
4. A
5. B
6. B
7. C
8. B
9. C
10. C
11. C
12. D
13. A
14. B
15. D
16. C
17. A
18. A
19. B
20. D
21. B
22. D
23. D
24. A
25. D
26. B
27. A
28. A
29. A
30. C

[MohamedBarghush]

Thanks, that will surely help.