Electronics - Introduction To Semiconductor Theory
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This includes semiconductor theory and diodes.
- 1.Every known element has
- A.
The same type of atoms
- B.
the same number if atoms
- C.
A unique type of atom
- D.
Several different types of atoms
- 2.An atom consists of
- A.
One nucleus and only one electron
- B.
One nucleus and one or more electrons
- C.
Protons, electrons, and neutrons
- D.
Answers (b) and (c)
- 3.The nucleus of an atom is made up of
- A.
Protons and neutrons
- B.
Electrons
- C.
Electrons and protons
- D.
Electrons and neutrons
- 4.The atomic number of silicon is
- A.
8
- B.
2
- C.
4
- D.
14
- 5.The atomic number of germanium is
- A.
8
- B.
2
- C.
4
- D.
32
- 6.The valence shell in a silicon atom has the number designation of
- A.
0
- B.
1
- C.
2
- D.
3
- 7.Valence electrons are
- A.
In the closest orbit to the nucleus
- B.
In the most distant orbit from the nucleus
- C.
In various orbits around the nucleus
- D.
Not associated with a particular atom
- 8.A positive ion is formed when
- A.
A valence electron breaks away from the atom
- B.
there are more holes than electrons in the outer orbit
- C.
Two atoms bond together
- D.
An atom gains an extra valence electron
- 9.The most widely used semiconductive material in electronic devices is
- A.
Germanium
- B.
Carbon
- C.
Copper
- D.
Silicon
- 10.The energy band in which free electrons exist is the
- A.
First band
- B.
Second band
- C.
Conduction band
- D.
Valence band
- 11.Electron-hole pairs are produced by
- A.
Recombination
- B.
Thermal energy
- C.
Ionization
- D.
Doping
- 12.Recombination is when
- A.
An electron falls into a hole
- B.
A positive and a negative ion bond together
- C.
A valence electron becomes a conduction electron
- D.
A crystal is formed
- 13.In a semiconductor crystal, the atoms are held together by
- A.
The interaction of valence electrons
- B.
Forces of attraction
- C.
Covalent bonds
- D.
Answers (A), (B), and (C)
- 14.Each atom in a silicon crystal has
- A.
Four valence electrons
- B.
Four conduction electrons
- C.
Eight valence electrons, four of its own and four shared
- D.
No valence electrons because all are shared with other atoms
- 15.The current in a semiconductor is produced by
- A.
Electron only
- B.
Holes only
- C.
Negative ions
- D.
Both electrons and holes
- 16.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 many electrons as there are holes
- E.
Answers (B) and (D)
- 17.The difference between an insulator and a semiconductor is
- A.
A wider energy gap between the valence band and the conduction band
- B.
The number of free electrons
- C.
The atomic structure
- D.
Answers (A), (B), and (C)
- 18.The process of adding an impurity to an intrinsic semiconductor is called
- A.
Doping
- B.
Recombination
- C.
Atomic modification
- D.
Ionization
- 19.The trivalent impurity is added to silicon to create
- A.
Germanium
- B.
A p-type semiconductor
- C.
An n-type semiconductor
- D.
A depletion region
- 20.The purpose of pentavalent impurity is to
- A.
Reduce the conductivity of silicon
- B.
Increase the number of holes
- C.
Increase the number of free electrons
- D.
Create minority carriers
- 21.The majority carriers in an n-type semiconductor are
- A.
Holes
- B.
Valence electrons
- C.
Conduction electrons
- D.
Protons
- 22.Holes in an n-type semiconductor are
- A.
Minority carriers that are thermally produced
- B.
Minority carriers that are produced by doping
- C.
Majority carriers that are thermally produced
- D.
Majority carriers that are produced by doping
- 23.A pn junction is formed by
- A.
The recombination of electrons and holes
- B.
Ionization
- C.
The boundary of a p-type and an n-type material
- D.
The collision of a proton and a neutron
- 24.The depletion region is created by
- A.
Ionization
- B.
Diffusion
- C.
Recombinations
- D.
Answers (A), (B), and (C)
- 25.The depletion region consists of
- A.
Nothing but minority carriers
- B.
Positive and negative ions
- C.
No majority carriers
- D.
Answers (B) and (C)
- 26.The term bias means
- A.
The ratio of majority carriers to minority carriers
- B.
The amount of current across the diode
- C.
A dc voltage is applied to control the operation of a device
- D.
Neither (A), (B), nor (C)
- 27.To forward-bias a diode,
- A.
An external voltage is applied that is positive at the anode and negative at the cathode
- B.
An external voltage is applied that is negative at the anode and positive at the cathode
- C.
An external voltage is applied that is positive at the p region and negative at the n region
- D.
Answers (A) and (C)
- 28.When a diode is forward-biased,
- A.
The only current is hole current
- B.
The only current is electron current
- C.
The only current is produced by the majority carriers
- D.
The current is produced by both holes and electrons
- 29.Although current is blocked in reverse bias,
- A.
There is some current due to majority carriers
- B.
There is a very small current due to minority carriers
- C.
There is an avalanche current
- 30.For a silicon diode, the value of the forward-bias voltage typically
- A.
Must be greater than 0.3 V
- B.
Must be greater than 0.7 V
- C.
Depends on the width of the depletion region
- D.
Depends on the concentration of majority carriers
- 31.When forward-bias, a diode
- A.
Blocks current
- B.
Conducts current
- C.
Has high resistance
- D.
Drops a large voltage
- 32.When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to
- A.
The bias battery voltage
- B.
0 V
- C.
The diode barrier potential
- D.
The total circuit voltage
- 33.A silicon diode is in series with a 1.0kW resistor and a 5 V battery. If the anode is connected to the positve battery terminal, the cathode voltage with respect to the negative battery terminal is
- A.
0.7 V
- B.
0.3 V
- C.
5.7 V
- D.
4.3 V
- 34.The postive lead of an ohmmeter is connected to the anode of a diode and the negative lead is connected to the cathode. The diode is
- A.
Reversed-bias
- B.
Open
- C.
Forward-biased
- D.
Faulty
- E.
Answers (B) and (D)
- 35.Approximates real diode with a battery, a resistance, and an ideal diode
- A.
Simplified model
- B.
Non ideal device
- C.
Ideal device
- D.
Piecewise – linear model
- 36.What type of bias opposes the pn junction barrier?
- A.
No bias
- B.
Direct bias
- C.
Reverse bias
- D.
Forward bias
- 37.Semi-conductors which are doped with either N or P types of impurities are called _________.
- A.
Intrinsic
- B.
Extrinsic
- C.
P-type
- D.
N-type
- 38.How many junctions are there in a semiconductor diode?
- A.
Two
- B.
None
- C.
One
- D.
Four
- 39.In electricity, electric charge refers to __________.
- A.
Protons
- B.
Electrons
- C.
Neutrons
- D.
Atoms
- 40.Term used to described sudden reverse conduction of an electronic component caused by excess reverse voltage across the device.
- A.
Cut-off
- B.
Avalanched
- C.
Saturation
- D.
Reversion
- 41.Outer shell of an atom is _______
- A.
Electron
- B.
Proton
- C.
Depletion
- D.
Valence
- 42.A circuit that adds a dc level to an ac voltage using a diode and a capacitor.
- A.
Clamper
- B.
Filter
- C.
Full-wave rectifier
- D.
Half-wave rectifier
- 43.A capacitor in a power supply used to reduce the variation of the output voltage from a rectifier.
- A.
Clamper
- B.
Filter
- C.
Limiter
- D.
Regulator
- 44.The change in output voltage of a regulator for a given change in input voltage normally expressed as a percentage.
- A.
Line regulation
- B.
Load regulation
- C.
Ripple voltage
- D.
Surge resistance
- 45.Load regulation is determined by __________.
- A.
Changes in load current and input voltage
- B.
Changes in load current and output voltage
- C.
Changes in load resistance and input voltage
- D.
Changes in zener current and load current
- 46.If one of the diodes in a bridge full-wave rectifier opens, the output is _______.
- A.
0 V
- B.
One-fourth the amplitude of the input voltage
- C.
A half-wave rectified voltage
- D.
A 120 Hz voltage
- 47.A 10V peak-to-peak sinusoidal voltage is applied across a silicon diode and series resistor. The maximum voltage across the diode is ________.
- A.
9.3 V
- B.
5 V
- C.
0.7 V
- D.
10 V
- E.
4.3 V
- 48.If the load resistance of a capacitor-filtered full-wave rectifier is reduced, the ripple voltage _________.
- A.
Increases
- B.
Decreases
- C.
Is not affected
- D.
Has a different frequency
- 49.When a 60 Hz sinusoidal voltage is applied to the input of a full-wave rectifier, the output frequency is ______.
- A.
120 Hz
- B.
60 Hz
- C.
240 Hz
- D.
0 Hz
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