Electronics - Introduction To Semiconductor Theory

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Semiconductor Quizzes & Trivia

This includes semiconductor theory and diodes.


Questions and Answers
  • 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

    Correct Answer
    C. A unique type of atom
    Explanation
    Every known element is characterized by a unique type of atom. Each element is defined by the number of protons in the nucleus of its atoms, which gives it a distinct atomic number. This unique atomic structure determines the element's chemical properties and distinguishes it from other elements. Therefore, the correct answer is that every known element has a unique type of atom.

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  • 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)

    Correct Answer
    D. Answers (b) and (c)
    Explanation
    An atom consists of a nucleus, which contains protons and neutrons, and one or more electrons that orbit around the nucleus. This means that both options (b) and (c) are correct, as they include the necessary components of an atom.

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  • 3. 

    The nucleus of an atom is made up of

    • A.

      Protons and neutrons

    • B.

      Electrons

    • C.

      Electrons and protons

    • D.

      Electrons and neutrons

    Correct Answer
    A. Protons and neutrons
    Explanation
    The nucleus of an atom is made up of protons and neutrons. Protons have a positive charge and are responsible for determining the atomic number of an element. Neutrons have no charge and are responsible for adding mass to the nucleus. Electrons, on the other hand, are found outside the nucleus in electron shells and have a negative charge. Therefore, the correct answer is protons and neutrons.

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  • 4. 

    The atomic number of silicon is

    • A.

      8

    • B.

      2

    • C.

      4

    • D.

      14

    Correct Answer
    D. 14
    Explanation
    The atomic number of an element represents the number of protons in the nucleus of its atom. In this case, the element is silicon, and the correct atomic number is 14. This means that a silicon atom has 14 protons in its nucleus.

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  • 5. 

    The atomic number of germanium is

    • A.

      8

    • B.

      2

    • C.

      4

    • D.

      32

    Correct Answer
    D. 32
    Explanation
    Germanium is an element that belongs to the periodic table and has an atomic number of 32. The atomic number represents the number of protons in the nucleus of an atom. In the case of germanium, it has 32 protons, which determines its atomic number. This number is unique to each element and helps in identifying and organizing them in the periodic table. Therefore, the correct answer is 32.

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  • 6. 

    The valence shell in a silicon atom has the number designation of

    • A.

      0

    • B.

      1

    • C.

      2

    • D.

      3

    Correct Answer
    D. 3
    Explanation
    The valence shell in a silicon atom has the number designation of 3 because silicon has an atomic number of 14, which means it has 14 electrons. The electronic configuration of silicon is 1s2 2s2 2p6 3s2 3p2. The valence shell is the outermost shell, which in this case is the third shell (designated by the number 3).

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  • 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

    Correct Answer
    B. In the most distant orbit from the nucleus
    Explanation
    Valence electrons are the electrons located in the outermost energy level or shell of an atom. These electrons are involved in chemical bonding and determining the reactivity of an atom. The valence electrons are found in the most distant orbit from the nucleus, as they are the furthest away from the positive charge of the nucleus.

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  • 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

    Correct Answer
    A. A valence electron breaks away from the atom
    Explanation
    When a valence electron breaks away from the atom, it leaves behind a positively charged ion. This is because the electron, which carries a negative charge, is no longer balanced by an equal number of protons in the nucleus. As a result, the atom becomes positively charged.

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  • 9. 

    The most widely used semiconductive material in electronic devices is

    • A.

      Germanium

    • B.

      Carbon

    • C.

      Copper

    • D.

      Silicon

    Correct Answer
    D. Silicon
    Explanation
    Silicon is the most widely used semiconductive material in electronic devices because it has several advantageous properties. It is abundant, cost-effective, and has a high melting point, making it suitable for manufacturing processes. Silicon also has a stable crystal structure, allowing for reliable performance. Additionally, it can easily be doped with impurities to alter its conductivity, making it versatile for various applications in electronics.

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  • 10. 

    The energy band in which free electrons exist is the  

    • A.

      First band

    • B.

      Second band

    • C.

      Conduction band

    • D.

      Valence band

    Correct Answer
    C. Conduction band
    Explanation
    The conduction band is the energy band in which free electrons exist. In a solid material, electrons are bound to atoms in the valence band, but when energy is supplied, some electrons can move to higher energy levels, creating a conductive pathway in the conduction band. This allows for the flow of electric current in materials. The first and second bands are not specifically related to the existence of free electrons, and the valence band is the energy band in which electrons are tightly bound to atoms.

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  • 11. 

    Electron-hole pairs are produced by

    • A.

      Recombination

    • B.

      Thermal energy

    • C.

      Ionization

    • D.

      Doping

    Correct Answer
    B. Thermal energy
    Explanation
    Electron-hole pairs are produced by thermal energy. When a material is heated, the thermal energy causes the atoms or molecules to vibrate and collide with each other. These collisions can provide enough energy to separate an electron from its atom, leaving behind a positively charged hole. The thermal energy is responsible for creating the necessary conditions for this process to occur and generate electron-hole pairs.

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  • 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

    Correct Answer
    A. An electron falls into a hole
    Explanation
    Recombination refers to the process in which an electron, which was previously excited to a higher energy level, falls back to its original energy level or "hole". This process can occur in semiconductors, where an electron from the conduction band recombines with a hole in the valence band, resulting in the release of energy in the form of light or heat. Therefore, the statement "an electron falls into a hole" accurately describes the process of recombination.

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  • 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)

    Correct Answer
    D. Answers (A), (B), and (C)
    Explanation
    In a semiconductor crystal, the atoms are held together by the interaction of valence electrons, forces of attraction, and covalent bonds. Valence electrons are the outermost electrons in an atom's electron shell, and their interaction with other atoms helps to hold the crystal structure together. Additionally, there are forces of attraction between the positively charged atomic nuclei and the negatively charged electrons. Lastly, covalent bonds occur when atoms share electrons, which further contribute to the stability of the crystal structure. Therefore, all of these factors play a role in holding the semiconductor crystal together.

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  • 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

    Correct Answer
    C. Eight valence electrons, four of its own and four shared
    Explanation
    Each atom in a silicon crystal has eight valence electrons, four of its own and four shared. This is because silicon belongs to Group 14 of the periodic table, which means it has four valence electrons in its outermost energy level. These four valence electrons are involved in covalent bonding with neighboring silicon atoms, resulting in the sharing of four electrons with each adjacent atom. Therefore, each silicon atom in the crystal has a total of eight valence electrons, with four belonging to itself and four being shared with other atoms.

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  • 15. 

    The current in a semiconductor is produced by

    • A.

      Electron only

    • B.

      Holes only

    • C.

      Negative ions

    • D.

      Both electrons and holes

    Correct Answer
    D. Both electrons and holes
    Explanation
    In a semiconductor, the current is produced by both electrons and holes. Semiconductors have a unique property where they can conduct electricity through the movement of both types of charge carriers. Electrons are negatively charged particles that move through the conduction band, while holes are the absence of electrons and can be thought of as positively charged particles that move through the valence band. The movement of both electrons and holes contributes to the flow of current in a semiconductor material.

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  • 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)

    Correct Answer
    E. Answers (B) and (D)
    Explanation
    In an intrinsic semiconductor, the free electrons are thermally produced. This means that at room temperature, some of the electrons in the valence band gain enough energy to move to the conduction band, creating free electrons. Additionally, there are also holes present in an intrinsic semiconductor, which are essentially the absence of electrons in the valence band. Therefore, both options (B) and (D) are correct.

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  • 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)

    Correct Answer
    D. Answers (A), (B), and (C)
    Explanation
    The correct answer is answers (A), (B), and (C). The difference between an insulator and a semiconductor lies in a wider energy gap between the valence band and the conduction band, the number of free electrons, and the atomic structure.

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  • 18. 

      The process of adding an impurity to an intrinsic semiconductor is called

    • A.

      Doping

    • B.

      Recombination

    • C.

      Atomic modification

    • D.

      Ionization

    Correct Answer
    A. Doping
    Explanation
    Doping is the process of adding an impurity to an intrinsic semiconductor. This is done to alter its electrical properties and create either a p-type or n-type semiconductor. By introducing impurities, the number of charge carriers in the semiconductor can be increased or decreased, allowing for the control of conductivity. Doping is an essential step in the fabrication of most electronic devices, such as diodes and transistors.

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  • 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

    Correct Answer
    B. A p-type semiconductor
    Explanation
    Trivalent impurities, such as boron or aluminum, have three valence electrons. When they are added to silicon, which has four valence electrons, they create "holes" in the crystal lattice structure. These holes act as positive charge carriers, creating an excess of positive charge in the material. This results in the silicon becoming a p-type semiconductor, where the majority charge carriers are positive "holes" rather than negative electrons.

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  • 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

    Correct Answer
    C. Increase the number of free electrons
    Explanation
    Pentavalent impurities, such as phosphorus or arsenic, have five valence electrons in their outermost shell. When these impurities are added to silicon, they create extra electrons that are free to move within the crystal lattice. This increases the number of free electrons in the material, thereby increasing its conductivity. Therefore, the purpose of pentavalent impurities is to increase the number of free electrons in silicon.

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  • 21. 

    The majority carriers in an n-type semiconductor are

    • A.

      Holes

    • B.

      Valence electrons

    • C.

      Conduction electrons

    • D.

      Protons

    Correct Answer
    C. Conduction electrons
    Explanation
    In an n-type semiconductor, the majority carriers are conduction electrons. N-type semiconductors are doped with impurities that introduce extra electrons into the crystal lattice. These extra electrons are called donor electrons and they become the majority carriers in the material. These conduction electrons are responsible for the flow of current in n-type semiconductors.

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  • 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

    Correct Answer
    A. Minority carriers that are thermally produced
    Explanation
    Holes in an n-type semiconductor are minority carriers that are thermally produced. In an n-type semiconductor, the majority carriers are electrons, which are produced by doping with impurities. However, due to thermal energy, some covalent bonds in the crystal lattice can break, creating holes. These holes act as positive charge carriers and can move through the material. Since holes are not the dominant carriers in an n-type semiconductor, they are considered minority carriers. The thermal energy in the material is responsible for generating these holes.

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  • 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

    Correct Answer
    C. The boundary of a p-type and an n-type material
    Explanation
    A pn junction is formed by the boundary of a p-type and an n-type material. In a p-type material, there is an excess of positively charged holes, while in an n-type material, there is an excess of negatively charged electrons. When these two materials are brought together, the electrons from the n-type material diffuse into the p-type material, recombining with the holes. This creates a region near the junction where there is a depletion of charge carriers, forming the pn junction. This junction plays a crucial role in the operation of various electronic devices such as diodes and transistors.

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  • 24. 

    The depletion region is created by

    • A.

      Ionization

    • B.

      Diffusion

    • C.

      Recombinations

    • D.

      Answers (A), (B), and (C)

    Correct Answer
    D. Answers (A), (B), and (C)
    Explanation
    The depletion region is created by a combination of processes, including ionization, diffusion, and recombinations. Ionization occurs when electrons are separated from atoms, creating positively charged ions and negatively charged electrons. Diffusion refers to the movement of these charged particles from areas of high concentration to areas of low concentration, leading to the formation of the depletion region. Recombinations occur when the separated charges recombine, neutralizing the region. Therefore, all of the given answers (A), (B), and (C) contribute to the creation of the depletion region.

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  • 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)

    Correct Answer
    D. Answers (B) and (C)
    Explanation
    The depletion region in a semiconductor device is formed when a p-n junction is created. It consists of positive and negative ions, which are formed due to the migration of majority carriers across the junction. The positive ions are created in the n-region and the negative ions in the p-region, resulting in the formation of an electric field. This electric field prevents the flow of majority carriers, hence there are no majority carriers in the depletion region. Therefore, the correct answer is (B) and (C).

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  • 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)

    Correct Answer
    C. A dc voltage is applied to control the operation of a device
    Explanation
    The term bias refers to the application of a direct current (dc) voltage to control the operation of a device. This bias voltage helps in regulating the behavior and characteristics of the device, such as its current flow or voltage output. It is used to establish a desired operating point or to enable certain functionalities in electronic circuits. Therefore, the correct answer is "a dc voltage is applied to control the operation of a device".

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  • 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)

    Correct Answer
    D. Answers (A) and (C)
    Explanation
    When forward-biasing a diode, an external voltage is applied in such a way that the anode is positive and the cathode is negative. This creates a positive potential at the p region and a negative potential at the n region, allowing current to flow through the diode. Therefore, both answer (A) and answer (C) are correct explanations for forward-biasing a diode.

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  • 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

    Correct Answer
    D. The current is produced by both holes and electrons
    Explanation
    When a diode is forward-biased, the current is produced by both holes and electrons. In a forward-biased diode, the positive terminal of the voltage source is connected to the p-type region and the negative terminal is connected to the n-type region. This causes the majority carriers (electrons in the n-type region and holes in the p-type region) to move towards the junction. Electrons move from the n-type region to the p-type region and combine with holes, creating a flow of current. Therefore, both electrons and holes contribute to the current in a forward-biased diode.

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  • 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

    Correct Answer
    B. There is a very small current due to minority carriers
    Explanation
    In a reverse biased diode, the majority carriers are blocked from flowing due to the applied voltage. However, there is still a very small current that flows due to the minority carriers. These minority carriers, which are present in very low concentrations, are able to move across the junction and contribute to a small current. This current is typically very small compared to the current that flows in forward bias, but it is still present in reverse bias.

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  • 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

    Correct Answer
    B. Must be greater than 0.7 V
    Explanation
    The forward-bias voltage for a silicon diode must be greater than 0.7 V because this is the typical threshold voltage required for the diode to conduct current in the forward direction. Below this voltage, the diode remains in a non-conductive state. The 0.7 V threshold is a characteristic of silicon diodes and is commonly used as a rule of thumb for their operation.

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  • 31. 

    When forward-bias, a diode

    • A.

      Blocks current

    • B.

      Conducts current

    • C.

      Has high resistance

    • D.

      Drops a large voltage

    Correct Answer
    B. Conducts current
    Explanation
    When a diode is forward-biased, it allows current to flow through it. This is because the forward biasing creates a potential difference across the diode, causing the free electrons to move towards the positive terminal and the holes towards the negative terminal. This movement of charge carriers enables the current to flow through the diode, making it conductive. Therefore, the correct answer is "conducts current."

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  • 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

    Correct Answer
    C. The diode barrier potential
    Explanation
    When a voltmeter is placed across a forward-biased diode, it will read a voltage approximately equal to the diode barrier potential. This is because the diode barrier potential is the voltage required for current to flow through the diode in the forward direction. Therefore, when the diode is forward-biased, the voltmeter will measure a voltage close to the barrier potential.

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  • 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

    Correct Answer
    D. 4.3 V
    Explanation
    When a silicon diode is in series with a resistor and a battery, the voltage across the diode is typically around 0.7 V. In this case, the anode of the diode is connected to the positive battery terminal, so the voltage at the cathode will be the battery voltage minus the diode voltage drop. Therefore, the cathode voltage with respect to the negative battery terminal will be 5 V - 0.7 V = 4.3 V.

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  • 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)

    Correct Answer
    C. Forward-biased
    Explanation
    When the positive lead of an ohmmeter is connected to the anode of a diode and the negative lead is connected to the cathode, it means that the diode is connected in the forward-biased configuration. In this configuration, the diode allows current to flow from the anode to the cathode, and the voltage drop across the diode is typically around 0.7 volts. Therefore, the correct answer is forward-biased.

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  • 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

    Correct Answer
    D. Piecewise – linear model
    Explanation
    A piecewise-linear model approximates a real diode by using a combination of a battery, a resistance, and an ideal diode. This model breaks down the behavior of the diode into different regions, where each region is represented by a linear equation. This allows for a simplified representation of the diode's characteristics, making it easier to analyze and understand its behavior in different circuit configurations. This model is considered a non-ideal device because it does not perfectly capture all the nuances and complexities of a real diode, but it provides a good approximation for most practical purposes.

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  • 36. 

    What type of bias opposes the pn junction barrier?

    • A.

      No bias

    • B.

      Direct bias

    • C.

      Reverse bias

    • D.

      Forward bias

    Correct Answer
    D. Forward bias
    Explanation
    Forward bias is the type of bias that opposes the pn junction barrier. When a forward bias is applied to a pn junction, the positive terminal of the battery is connected to the p-side of the junction and the negative terminal is connected to the n-side. This causes the depletion region to become narrower, allowing current to flow more easily across the junction. In other words, forward bias reduces the opposition to current flow at the pn junction barrier.

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  • 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

    Correct Answer
    B. Extrinsic
    Explanation
    Extrinsic semi-conductors are those that have been intentionally doped with impurities, either N or P types. This doping process alters the electrical properties of the semi-conductor material, allowing it to conduct electricity more efficiently. In contrast, intrinsic semi-conductors do not contain any intentional impurities and have their electrical properties solely determined by the material itself. Therefore, the correct answer is extrinsic.

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  • 38. 

     How many junctions are there in a semiconductor diode?

    • A.

      Two

    • B.

      None

    • C.

      One

    • D.

      Four

    Correct Answer
    C. One
    Explanation
    A semiconductor diode typically consists of a p-n junction, where a p-type semiconductor material and an n-type semiconductor material are joined together. This junction is the main component of a diode and is responsible for its functionality. Therefore, the correct answer is "one," as there is only one junction in a semiconductor diode.

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  • 39. 

    In electricity, electric charge refers to __________.

    • A.

      Protons

    • B.

      Electrons

    • C.

      Neutrons

    • D.

      Atoms

    Correct Answer
    B. Electrons
    Explanation
    Electric charge refers to the property of matter that causes it to experience a force when placed in an electromagnetic field. Electrons are negatively charged particles that are responsible for carrying electric charge in most common electrical phenomena. Therefore, in the context of electricity, electric charge refers to electrons.

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  • 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

    Correct Answer
    B. Avalanched
    Explanation
    Avalanched is the correct answer because it accurately describes the sudden reverse conduction of an electronic component caused by excess reverse voltage across the device. The term "avalanched" suggests a rapid and intense flow or movement, which aligns with the sudden reversal of conduction in the component due to excessive reverse voltage. This term effectively conveys the concept of a sudden and dramatic change in the behavior of the electronic component.

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  • 41. 

    Outer shell of an atom is _______

    • A.

      Electron

    • B.

      Proton

    • C.

      Depletion

    • D.

      Valence

    Correct Answer
    D. Valence
    Explanation
    The outer shell of an atom is referred to as the valence shell. This shell contains the valence electrons, which are the electrons involved in the atom's chemical reactions and bonding with other atoms. The number of valence electrons determines the atom's reactivity and its ability to form bonds. Therefore, the correct answer is valence.

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  • 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

    Correct Answer
    A. Clamper
    Explanation
    A clamper circuit is used to add a DC level to an AC voltage using a diode and a capacitor. The diode allows the current to flow in only one direction, while the capacitor stores and releases charge. When the input AC voltage is applied, the diode conducts during the positive half-cycle, allowing the capacitor to charge to the peak value of the input voltage. During the negative half-cycle, the diode blocks the current flow, but the capacitor maintains the voltage level, resulting in a DC level added to the AC voltage. Therefore, a clamper circuit is the correct answer.

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  • 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

    Correct Answer
    B. Filter
    Explanation
    A filter is used in a power supply to reduce the variation of the output voltage from a rectifier. It helps to smooth out any fluctuations or ripples in the voltage, ensuring a more stable and constant output. This is achieved by allowing only the desired frequencies to pass through while attenuating or blocking unwanted frequencies. By using a filter, the power supply can provide a more consistent and reliable voltage to the connected devices.

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  • 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

    Correct Answer
    A. Line regulation
    Explanation
    Line regulation refers to the ability of a regulator to maintain a consistent output voltage despite changes in the input voltage. It is expressed as a percentage, indicating the change in output voltage for a given change in input voltage. This means that a regulator with good line regulation will have a smaller percentage change in output voltage for a given change in input voltage, indicating better stability and reliability in maintaining the desired output voltage.

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  • 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

    Correct Answer
    B. Changes in load current and output voltage
    Explanation
    Load regulation refers to the ability of a power supply to maintain a stable output voltage despite changes in the load current. When the load current increases or decreases, it can cause fluctuations in the output voltage. Similarly, changes in the output voltage can also affect the load current. Therefore, load regulation is determined by changes in both load current and output voltage.

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  • 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

    Correct Answer
    C. A half-wave rectified voltage
    Explanation
    If one of the diodes in a bridge full-wave rectifier opens, it means that it is no longer conducting current. This will result in only one half of the input AC waveform being rectified, while the other half will be blocked. Therefore, the output will be a half-wave rectified voltage, with only the positive half-cycles being present in the output waveform.

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  • 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

    Correct Answer
    B. 5 V
    Explanation
    In a circuit comprising a silicon diode and a series resistor, an alternating voltage with a peak-to-peak value of 10 volts is applied. The maximum voltage across the diode can be determined by taking half of the peak-to-peak voltage. Applying this method to the given peak-to-peak voltage of 10 volts yields a maximum voltage across the silicon diode of 5 volts.
     

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  • 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

    Correct Answer
    A. Increases
    Explanation
    When the load resistance of a capacitor-filtered full-wave rectifier is reduced, the ripple voltage increases. This is because a lower load resistance allows more current to flow through the capacitor, resulting in a larger voltage drop across it during the discharge phase. As a result, the difference between the maximum and minimum voltage levels, known as the ripple voltage, becomes greater.

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  • 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

    Correct Answer
    A. 120 Hz
    Explanation
    When a 60 Hz sinusoidal voltage is applied to the input of a full-wave rectifier, the output frequency is 120 Hz. This is because a full-wave rectifier converts both the positive and negative halves of the input waveform into positive pulses. Therefore, the output waveform will have twice the frequency of the input waveform, resulting in an output frequency of 120 Hz.

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