Questão 1
Questão
If a semiconductor is brought down to temperature of absolute zero (0 Kelvin), it will become:
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A conductor
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A superconductor
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An insulator
Questão 2
Questão
According to Band Theory of Solids, what can be said about the relationship between band-gap width and the tendency of material to conduct electricity?
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The greater the band-gap width the less conductive is the material
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The lesser the band-gap width the more insulating is the material
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The greater the band-gap width the more conductive is the material
Questão 3
Questão
According to Band Theory of Solids, what can be said about P- and N- type conductivity with regard to the location of the electron bands?
Responda
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P and N type conductivities are in the conduction band
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P-type conductivity is in the conduction band, and N-conductivity is in the valence band
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P-type conductivity is in the valence band, and N-conductivity is in the conduction band
Questão 4
Questão
What are the respective current carriers for N- and P-type conductivity?
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Electrons
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P-type carriers are “holes”, and N-type are electrons
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P-type are positrons, and N-type are “holes”
Questão 5
Questão
Typical semiconductors such as Silicon and Germanium are group IV elements. Choose the correct statement regarding the doping and the type of conductivity (N or P) acquired, after doping:
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P-type conductivity is achieved by doping with elements from group V, and N-type conductivity is achieved by doping with elements from group III
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Both types are achieved from doping with group IV
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P-type conductivity is achieved by doping with elements from group III, and N-type conductivity is achieved by doping with elements from group V
Questão 6
Questão
What is the relationship between N- and P- type charge carriers for intrinsic (undoped) semiconductors?
Questão 7
Questão
For semiconducting materials, charge carrier species called holes are best described as:
Questão 8
Questão
In doped (extrinsic) semiconductors, the predominant current carriers are called majority charge carriers, and secondary carriers are called minority. Which statement is true for N-and P-type semiconductors:
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In N-type semiconductors, electrons are majority carriers and holes are minority carriers
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In P-type semiconductors, majority carriers are electrons, and minority charge carriers are holes
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In N-type semiconductors, both types of carriers are equally present
Questão 9
Questão
Transistors are made of N- and P-type semiconductors arranged in a such way that:
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There are two p-n junctions
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There are three p-n junctions
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There is one p-n junction
Questão 10
Questão
The two main functions of the transistor are:
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Polarizer and oscillator
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Amplifier and switch
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Rectifier and attenuator
Questão 11
Questão
Choose the FALSE statement. Electrical amplifiers are used for:
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Voltage
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Frequency
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Current
Questão 12
Questão
The magnitude of electrical impedance of biological tissues is the (Pythagorean) sum of:
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Resistance and capacitive reactance
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Inductive and capacitive reactance
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Resistance and inductive reactance
Questão 13
Questão
What type of transducer is the piezoelectric crystal in ultrasonic equipment, when working in receiving mode?
Questão 14
Questão
The “band gap” in semiconductor theory is defined as:
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The distance between valence and conduction bands
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The frequency gap between AM and FM radio bands
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The energy gap between valence and conduction bands
Questão 15
Questão
When temperature increases, the band gap in a semiconductor:
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Increases, due to increased kinetic energy of atoms
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Remains the same, because electrons are bound in their orbits
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Decreases, due to electron-phonon interactions
Questão 16
Questão
When semiconductor is doped with element of lower valence (P-type doping) it becomes a donor (gives off electrons) and there is a shift in the energy band gap. The new electron levels are:
Questão 17
Questão
When temperature increases, the conductivity of semiconductors:
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Increases
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Decreases
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Remains the same
Questão 18
Questão
When semiconductor is doped with element of higher valence (N-type doping) it becomes an acceptor (takes electrons) and there is a shift in the energy band gap. The new electron levels are:
Questão 19
Questão
When Silicon (Si) is doped with one of the following elements, it acquires P-type conductivity (holes are the majority carriers). Choose the one:
Questão 20
Questão
Electric circuit components composed of single p-n junction are called:
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Capacitors
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Transistors
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Diodes
Questão 21
Questão
What is the mathematical relation between the electrical resistance (R) in a semiconductor and the temperature (T)?
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Linear (as T increases, R decreases with constant rate)
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Proportional (as T increases, R increases with constant rate)
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Exponential decay (as T increases, R decreases with increasing rate)
Questão 22
Questão
What is the mathematical relationship between the generated voltage in a photodiode and the distance from the light source?
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Quadratic (voltage increase as the square of the distance)
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Inversely proportional (decreases as one over the distance)
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Exponential (increases with increasing rate)
Questão 23
Questão
Which of the following statements is true about the element Germanium?
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The resistivity at room temperature is lower than that of Copper
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When heated the resistivity decreases
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The resistivity is constant over a wide range
Questão 24
Questão
The most common material in modern integrated circuits is: