Semiconductors

What is the smallest element of matter?
a. Neutron
b. Electrons
c. Protons
d. Atom

d. Atom

The definite discrete amount of energy required to move an electron from a lower shell to a higher shell?
a. Quanta
b. Negative energy
c. Quantum
d. Positive energy

c. Quantum

What will happen to an atom if an electron is either taken out or taken into the same atom?
a.Becomes negative ion
b.Becomes an ion
c.Becomes positive ion
d.Nothing will happen

b. Becomes an ion.

When an atom gains additional ______, it results to a negative ion
a.atom
b.neutron
c.electron
d.proton

c. Electron

Amount of additional energy required for the electronic emission of metals?
a. Electronvolt
b. Work function
c. Band gap
d. MeV

b. Work function

Emission of electrons from a material by application of a very high voltage?
a. Secondary emission
b. Thermionic emission
c. High field emission
d. Photoelectric emission

c. High field emission

Another name for a vacuum tube diode?
a. Fleming valve
b. Audion
c. Thyratron
d. Detector

a. Fleming valve

How many electrodes does a pentode have?
a. Four
b. Two
c. Three
d. Five

d. Five

What is the gain of a vacuum tube having the following parameters: amplification factor is 80, external plate-load resistance of 30,000 ohms, and the tube’s internal plate resistance is 10,000 ohms?
a. 60
b. 20
c. 30
d. 40

a. 60

Triodes are usually rated by their?
a. µ
b. gm
c. rp
d. Voltage gain

a. µ (Amplification factor)

Which terminal of the tetrode is nearest to its anode?
a. Screen grid
b. Cathode
c. Suppressor grid
d. Control grid

a. Screen grid

Which of the VT devices has secondary emission as a major problem?
a. Triode
b. Pentode
c. Tetrode
d. Hexode

c. Tetrode

The _____ grid in an electron tube is where the input signal is usually applied.
a. Screen
b. Control
c. Bias
d. Suppression

b. Control grid

A heptode tube has how many grids?
a. Seven
b. One
c. Five
d. Three

a. Seven

______ is a gaseous tube that uses a pool of liquid mercury as its cathode.
a. Thyratron
b. Phanatron
c. Klystron
d. Ignitron

d. Ignitron

Thyratrons in industrial electronics refer to _______.
a. A gas-filled diode
b. A vacuum tube
c. A gas-filled triode
d. An electron triode

c. A gas-filled triode

_____ is a low-frequency oscillation which sometimes occurs under fault conditions in electron tube circuits.
a. Ping pong
b. Jitter
c. Glitch
d. Motor boating

d. Motor boating

_____ are electrons at the outer shell.
a. Valence electrons
b. Inside shell electrons
c. Outside shell electrons
d. Conductor electrons

a. Valence electrons

A good material conductor should have ____ valence electrons.
a. 21
b. 10
c. 1
d. 3.5

c. 1

The difference in energy between the valence and conduction bands of a semiconductor is called?
a. Band gap
b. Extrinsic photo effect
c. Conductivity
d. Energy density

a. Band gap

What elements possess four valence electrons?
a. Insulators
b. Semi-insulators
c. Semiconductors
d. Conductors

c. Semiconductors

What two elements are widely used in semiconductor devices that exhibit both metallic and non-metallic characteristics?
a. Galena and Germanium
b. Silicon and Gold
c. Galena and Bismuth
d. Silicon and Germanium

d. Silicon and Germanium

This happens when a free electron returns to the valence shell.
a. Hole
b. Ionization
c. Recombination
d. Lifetime

c. Recombination

_____ has a unit of electronvolt (eV).
a. Current
b. Charge
c. Energy
d. Potential difference

c. Energy

The name of a pure semiconductor material that has an equal number of electrons and holes?
a. N-type
b. Pure type
c. Intrinsic
d. P-type

c. Intrinsic

What type of material is formed when trivalent material is doped with silicon or germanium?
a. N type
b. N & P type
c. PN type
d. P type

d. P type

Which is the majority carrier in an N-type semiconductor?
a. Electron
b. Positive ion
c. Negative ion
d. Hole

a. Electron

The arrow in the schematic symbol for a diode points which way?
a. Towards the cathode
b. In the direction of the current flow
c. Towards the anode
d. Towards magnetic north

a. Towards the cathode

The anode of a semiconductor diode indicates a __________ charge during conduction.
a. Positive
b. Either, depending on the design
c. Neutral
d. Negative

a. Positive

A point in the characteristic curve of a diode where the current suddenly rises.
a. Peak voltage
b. Knee voltage
c. Valley voltage
d. Trigger voltage

b. Knee voltage

The small value of direct current that flows when a semiconductor device has a reverse bias.
a. Surge current
b. Bias current
c. Reverse current
d. Current limit

c. Reverse current

In order to simplify a circuit, in analysis and computation, the diode is normally assumed as __________.
a. Zero
b. Ideal
c. Imaginary
d. Infinite

b. Ideal

An external voltage applied to a junction reduces its barrier and aids current to flow through the junction.
a. Reverse bias
b. External bias
c. Junction bias
d. Forward bias

d. Forward bias

How does an ohmmeter behave if its positive lead is connected to the cathode of a diode while negative to anode?
a. Has infinite high resistance
b. Has unstable resistance
c. Has very low resistance
d. Has decreasing resistance

a. Has infinite high resistance

It is the maximum permissible reverse voltage for the diode.
a. Peak reverse voltage
b. Barrier voltage
c. Maximum voltage
d. Tolerable voltage

a. Peak reverse voltage

Circuit that is used to eliminate or portions of the input waveform above or below a specified level.
a. Clamper
b. Clipper
c. DC restorer
d. Multiplier

b. Clipper

Which is not an application of clipper?
a. Circuit transient protection
b. Changing the shape of the waveform
c. Detection
d. Oscillation

d. Oscillation

What is another name for clamper?
a. Slicer
b. Limiter
c. Clipper
d. DC restorer

d. DC restorer

Circuit that is used to produce a DC output voltage that is some integral multiple of the peak of the AC input voltage.
a. Integrator
b. Restorer
c. Differentiator
d. Multiplier

d. Multiplier

What is the process by which AC is converted to pulsating DC?
a. Charging
b. Rectification
c. Filtering
d. Clipping

b. Rectification

_________ is the output of a half-wave rectifier.
a. Half-wave rectified signal
b. Square wave signal
c. 100% AC signal
d. Sinusoidal signal

a. Half-wave rectified signal

How many diodes will you use to have a basic half-wave rectifier?
a. Three
b. Four
c. Two
d. One

d. One

The four basic circuit blocks that make up a power supply are?
a. Transformer, clipper, filter, regulator
b. Rectifier, clamper, filter, regulator
c. Transformer, rectifier, inverter, regulator
d. Transformer, rectifier, filter, regulator

d. Transformer, rectifier, filter, regulator

What is the ideal voltage regulation of a power supply?
a. 0%
b. 50%
c. 100%
d. 1%

a. 0%

It is a type of transformer whose secondary voltage is equal to the primary voltage and used to isolate electrically the power supply from the AC power line thus protecting the power supply and the technician who is working on it.
a. Autotransformer
b. Step-down transformer
c. Step-up transformer
d. Isolation transformer

d. Isolation transformer

Find the direct current voltage from a full-wave rectifier with 120V peak rectified voltage.
a. 60V
b. 7.639V
c. 76.39V
d. 6.0V

c. 76.39V

What is the maximum efficiency of a half-wave rectifier?
a. 50%
b. 40.6%
c. 81.2%
d. 100%

b. 40.6%

A half-wave rectifier circuit utilizing one half of an AC input cycle has a ripple frequency in its output equivalent to?
a. 60 cps
b. 120 cps
c. 110 cps
d. 240 cps

a. 60 cps

Find the ripple factor (kr) of sinusoidal signal with peak ripple of 4V on an average of 30.
a. 0.094
b. 0.013
c. 0.130
d. 0.940

a. 0.094

It the remaining variation in the output of a power supply filter.
a. Residual voltage
b. Ripple
c. Offset voltage
d. Persistent voltage

b. Ripple

A DC voltage supply is measured at 50V and drops to 45V when the load is connected. What is the value of “voltage regulation”?
a. 5%
b. 50%
c. 60%
d. 11.11%

d. 11.11%

How much voltage regulation does commercial power supply have?
a. 10%
b. 10% and above
c. 15% and above
d. Within 1%

d. Within 1%

What is the voltage regulation when the full-load voltage is the same as no-load voltage assuming a perfect voltage source?
a. 100%
b. 0%
c. 1%
d. 10%

b. 0%

_________ is a type of linear voltage used in applications where the load on the unregulated voltage source must be kept constant.
a. A series regulator
b. A constant current source
c. A shunt current source
d. A shunt regulator

d. A shunt regulator

__________ is a type of linear regulator used in applications requiring efficient utilization of the primary power source.
a. A series regulator
b. A shunt regulator
c. A constant current source
d. A shunt current source

a. A series regulator

It is the sudden current and voltage spike that has a small duration.
a. Transient
b. Vrms
c. Peak voltage
d. VDC

a. Transient

It is the component that is used to provide a discharge path for the capacitor in a voltage multiplier if the load opens.
a. Discharging path
b. Tuned circuit
c. Inductive path
d. Bleeder resistor

d. Bleeder resistor

How do you determine if a diode is defective?
a. Diode resistance is very low or very high in either direction
b. High current
c. Very low current
d. High voltage

a. Diode resistance is very low or very high in either direction

The term used to describe sudden reverse conduction of an electronic component caused by excess reverse voltage across the device is?
a. Cut-off
b. Saturation
c. Avalanche
d. Reversion

c. Avalanche

How are Zener diodes widely used?
a. Current limiter
b. Variable resistors
c. Voltage regulators
d. Power collectors

c. Voltage regulators

_______ is a PN junction semiconductor device that emits non-coherent optical radiation when biased in the forward direction, as a result of a recombination effect.
a. LASER
b. JUGPET
c. LED
d. Optical cavity

c. LED

What type of bias is required for an LED to produce luminescence?
a. Reverse bias
b. Zero bias
c. Forward bias
d. Inductive bias

c. Forward bias

What special type of diode is capable of both amplification and oscillation?
a. Point contact diode
b. Junction diode
c. Zener diode
d. Tunnel diode

d. Tunnel diode

Which is the principal characteristic of a tunnel diode?
a. A very high PIV
b. A high forward current rating
c. A high forward resistance
d. A negative resistance region

d. A negative resistance region

A high-speed diode with very small junction capacitance is called a?
a. Silicon diode
b. Schottky diode
c. Germanium diode
d. Tunnel diode

b. Schottky diode

Which is the principal characteristic of a varactor diode?
a. It has a very high PIV
b. It has a negative region
c. Its internal capacitance varies with the applied voltage
d. It has a constant voltage under conditions of varying current

c. Its internal capacitance varies with the applied voltage

It is the factor by which the capacitance of the varactor changes from one special value of reverse voltage to another.
a. Capacitance factor
b. Variance factor
c. Capacitance ratio
d. Reactance factor

c. Capacitance ratio

A varactor diode with a high capacitance ratio can be used in?
a. Tuning fork
b. Coarse tuning
c. Phase tuning
d. Fine tuning

b. Coarse tuning

It is a kind of tuning circuit that is used to vary the value of the resonant frequency over a wide range of frequencies.
a. Resonant circuit
b. Band wide circuit
c. Fine tuning circuit
d. Coarse tuning circuit

d. Coarse tuning circuit

It is a diode whose central material is made up of intrinsic silicon sandwiched by p and n-type materials.
a. PIN
b. Zener
c. Schottky
d. Tunnel

a. PIN

The type of diode that is made of a metal whisker touching a very small semiconductor die is?
a. Junction diode
b. Varactor diode
c. Point contact diode
d. Zener diode

c. Point contact diode

It is a circuit that uses two diodes to provide a DC output voltage equal to twice the AC voltage.
a. Voltage doubler
b. Voltage regulator
c. Voltage multiplier
d. All of these

a. Voltage doubler

Without a DC source, a clipper acts like a?
a. Rectifier
b. Clamper
c. Demodulator
d. Chopper

a. Rectifier

The main job of a voltage regulator is to provide a nearly __________ output voltage.
a. Sinusoidal
b. Constant
c. Smooth
d. Fluctuating

b. Constant

The average value of a half-wave rectified voltage with a peak value of 200V is?
a. 63.7V
b. 127.3V
c. 141V
d. 0V

a. 63.7V

When the peak output voltage is 100V, the PIV for each diode in the center-tapped full-wave rectifier is (neglecting the diode drop)?
a. 100V
b. 200V
c. 141V
d. 50V

b. 200V

When the RMS output voltage of a full-wave bridge rectifier is 20V, the peak inverse voltage across the diodes is (neglecting the diode drop)?
a. 20V
b. 40V
c. 28.3V
d. 56.6V

c. 28.3V

If the input voltage to a voltage tripler has an RMS value of 12V, the DC output voltage is approximately?
a. 36V
b. 50.9V
c. 33.9V
d. 32.4V

b. 50.9V

A transformer giving a secondary voltage of 9V RMS is used in a half-wave rectifier circuit. The peak inverse voltage across the diodes is?
a. 9V
b. 13V
c. 18V
d. 26V

b. 13V

A certain power supply filter produces an output with a ripple of 100mV peak-to-peak and a DC value of 20V. The ripple factor is?
a. 0.05
b. 0.005
c. 0.00005
d. 0.02

b. 0.005

The ripple of a filter output voltage with the following output signal measurement of VDC = 30V and Vrms = 1.5V is?
a. 9.5%
b. 95%
c. 5%
d. 50%

c. 5%

Find the voltage regulation giving a DC voltage of 67V without load and with full-load current drawn, the output voltage drops to 42V.
a. 59.5%
b. 62.7%
c. 15.9%
d. 32.5%

a. 59.5%