NEW
Font size
WorksheetsELECS 12
Total questions: 50
Worksheet time: 17mins
According to the classical Bohr model, the ________ is viewed as having a planetary-type structure.
atom
proton
electron
neutron
An n-type semi-conductive material is created by adding impurity atoms that have ________ valence electrons.
2
4
3
5
What composes an atom?
One nucleus and only one electron
Protons, electrons, and nucleus
One nucleus and only one proton
Electrons and protons only
What is nucleus of an atom?
It is made up of protons and neutrons.
Only protons are there.
Protons and electrons are within the nucleus.
It is composed only of neutrons.
What is the atomic number of silicon?
29
34
14
15
What is the atomic number of germanium?
29
34
32
15
What is the letter designation of the valence shell in a silicon atom?
M
N
O
L
Where are valence electrons found?
In the closest orbit to the nucleus
In various orbits around the nucleus
In the most distant orbit from the nucleus
In the nucleus of an atom
How is positive ion formed?
When a valence electron breaks away from the atom
When there are more holes than electrons in the outer orbit
When the two atoms bond together
When an atom gains an extra valence electron
How is negative ion formed?
When a valence electron breaks away from the atom
When there are more holes than electrons in the outer orbit
When the two atoms bond together
When an atom gains an extra valence electron
What is the most widely used semiconductor material in electronic devices?
Germanium
Silicon
Gallium
Arsenic
What energy band in which free electrons exists?
Valence band
Conduction band
First band
Second band
How are electron-hole pairs produced?
By recombination
By thermal energy
By ionization
By doping
When an electron falls into a hole this is
recombination
ionization
avalanche breakdown
doping
What hold together the atoms in a semiconductor crystal?
By covalent bonding
By forces of attraction
By the interaction of valence electrons
All of the choices
In a silicon crystal, each atom has
four conduction electrons
eight valence electrons, four of its own and four shared
four valence electrons
no valence electrons
What produces the current in a semiconductor?
The electrons only.
The holes only.
Negative ions only.
By both electrons and holes.
In an intrinsic semiconductor.
the free electrons are thermally produced.
there are as many free electrons as there are holes.
there are no free electrons.
Both A and B above.
What is the difference between semiconductor and an insulator?
The atomic structure.
The number of free electrons.
A wider energy gap between the valence band and the conduction band.
All of the choices.
What is the process of adding impurity to an intrinsic semiconductor?
Doping
Recombination
Ionization
Annihilation
What impurity is added to silicon to create a p-type semiconductor?
Trivalent
Pentavalent
Intrinsic
Extrinsic
What is the purpose of a pentavalent impurity?
To reduce the conductivity of silicon
To increase the number of holes
To create minority carriers
To increase number of free electrons
What are the majority carriers in an n-type semiconductor?
Valence electrons
Conduction electrons
Protons
Holes
What are holes in n-type semiconductor?
Majority carriers that are thermally produced.
Minority carriers that are thermally produced.
Majority carriers that are produced by doping.
Minority carriers that are produced by doping.
How is pn junction formed?
By the boundary of p-type and n-type material
By ionization
By collision of proton and neutron in the nucleus
By the recombination process
What creates the depletion region?
Ionization
Diffusion
Recombination
All of the choices
What are in the depletion region?
Positive and negative ions
Minority carriers
Majority carriers
All of the choices
What does the term bias mean?
The amount of current across the junction.
The ratio of majority to minority carriers.
The dc voltage applied to control the operation of the devices.
All of the choice
How to forward bias a pn junction diode?
By applying an external voltage that is positive to the anode and negative to the cathode
By applying an external voltage that is positive at the p-region and negative at the n-region
By applying an external voltage that is negative at the anode and positive to the cathode.
Either A and B above.
What happens when the pn junction is forward-biased?
The current is produced by both holes and electrons
Hole current is the only current
Electron current is only the current.
Majority carriers produced the only current.
What causes a very small current in reversed-bias condition?
Majority carriers
Minority carriers
Forward current
Reverse current
What is typically the forward-bias voltage for a silicon diode?
Greater than 0.7 V
Lesser than 0.7 V
Greater than 0.3 V.
Lesser than 0.3 V
When does a diode conduct current?
When applied with a voltage
When forward-biased
When reverse-biased
When power is on
What voltage is read by the voltmeter when connected across a forward-biased diode?
The diode barrier potential
The bias battery voltage
The total circuit voltage
0 V
If the positive lead of an ohmmeter is connected to the anode of a diode and the negative lead to the cathode then the diode is
reversed-biased
opened
shorted
forward-biased
What is the ideal dc output of a capacitor filter?
Equal to the rms value of the rectified voltage
Equal to the average value of the rectified voltage
Equal to the peak value of the rectified voltage
Equal to the peak-to-peak value of the input voltage
If the load resistance of a capacitor-filtered full-wave rectifier is reduced, the ripple voltage
increases
decreases
has a different frequency
is not affected
What is the output of full-wave bridge-type rectifier when one of the diodes opens?
0 V
A half-wave rectified voltage
A 120-Hz voltage
One fourth the amplitude of the input voltage
A virtual ground is a ground for
voltage but not for current
current but not for voltage
both current and voltage
neither current nor voltage
Normally in a zener voltage regulator the cathode is
more negative than the anode
more positive than the anode
at +0.7 V
grounded
What determines line regulation?
The load resistance
The load current
The changes in load resistance and output voltage
The changes in the output voltage and input voltage
What determines load regulation?
The changes in load current and input voltage
The changes in load current and output voltage
The changes in load resistance and input voltage
The changes in zener current and load current
What is a no-load condition?
The load has infinite resistance.
The load has zero resistance.
The output terminals are open.
Both A and C.
What is the maximum efficiency of a full-wave rectifier?
40.6%
20.3%
90%
81.2%
The dc output of the bridge type rectifier is nearly _________ than that of center tap circuit for a given transformer.
thrice
twice
four times
three times
In a center-tap circuit, __________ transformer secondary voltage is utilized.
one-half
full
one-third
one-eight
What is the maximum efficiency of a half-wave rectifier?
20.3%
80.6%
50%
40.6%
What rectifier circuit in which a transformer is essential?
Bridge type
Half-wave
Center-tap
Full-wave
In a full-wave rectifier, if ac supply is 50 Hz, then what is the ac ripple in the output?
50 Hz
100 Hz
25 Hz
200 Hz
How many diodes are used by a bridge type rectifier?
Two
Four
Three
Five
