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Note Book

Electrician Trade

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Electric Current

  1. One coulomb of electrical charge is contributed by how many electrons?

    Ans: 1

     

  2. 5 × 1016 electrons pass across the section of a conductor in 1 minutes and 20 seconds. The current is flowing

    Ans: 1

     

  3. An current of 6 A is same as

    Ans: 2

     

  4. Ampere - second is the unit of

    Ans: 4


     

  5. The current in a circuit follows the relation i = 100sinωt. If frequency is 25 Hz, how long will it take for thecurrent to rise to 50 A ?

    Ans: 2

  6. The equation of a current is given by i = Imsin2ωt. The frequency of the current in Hz is

    Ans: 4

     

  7. The equation of alternating current is i = 42.4sin628t. Then the average value of current is

    Ans: 2

  8. If 1 A current is flowing through a series circuit having 100 resistors of each having resistance of 1 Ω. What will be the current in the circuit where, these 100 resistors are connected in parallel?

     

     Ans: 4

  9. In the figure shown, what will be the current passing through 2 Ω resistor ?

    Ans: 1

     

  10. A copper conductor of one square millimeter can safely carry an current of

    Ans: 4

     

  11. For carrying an current of 75 A an aluminium conductor should have a minimum cross-section of

     

     Ans: 1

  12. A copper wire of length l and diameter d has potential difference V applied across its two ends. The drift velocity is Vd. If the diameter of the wire is made d / 2, then the drift velocity becomes

    Ans: 1

     

  13. Mass of a proton is how many times greater than mass of an electron?

     

     Ans: 3

  14. On which factors does the severity of electric shock depends ?

    Ans: 4

     

  15. Five coulomb of electrical charge is contributed by how many electrons?

     

     Ans: 1

  16. The transient current in a series AC circuit is given by

    Find the initial current ?

     

     Ans: 2

  17. Alternating current is found most suitable for

     

     Ans: 2

  18. The rms value of a half wave rectified symmetrical square wave current of 2 A is given by

    Ans: 3

     

  19. How many coulombs of charge flows through a circuit carrying 5 A in 5 min?

    Ans: 1

     

  1. The flow of current in solids is due to

    Ans: 2

     

  2. Ampere second could be the unit of

    Ans: 3

     

  3. The drift velocity of electrons is

    Ans: 1

     

  4. The charge on an electron is known to be 1.6 × 10-19coulomb. In a circuit the current flowing is 1 A. How many electrons will be flowing through the circuit in a second?

    Ans: 3



     

     

  5. In gases the flow of current is due to

    Ans: 4

     

  6. An current of 5 A is same as

    Ans: 2

     

  7. An instrument which detects current is known as

    Ans: 3

     

  8. Current flows in a circuit when

     

     Ans: 2

  9. Eight-tenths coulomb passes a point in 4 s. The currentin amperes is

    Ans: 4

     

  10. An ammeter is an electrical instrument used to measure

    Ans: 2

     

  11. The rate of flow an electric charge is known as

     

     Ans: 1

  12. The minimum requirement for causing flow of currentare

     

     Ans: 2

  13. Which of the following current is considered dangerous to the human body

    Ans: 2

     

  14. The ratio of voltage and electrical current in a closed circuit

     

     Ans: 4

  15. Current velocity through the copper conductor is

    Ans: 1

     

  16. Which of the following statements is true?

    Ans: 3

     

  17. An electric bulb can be worked from

     

     Ans: 4

  18. Electric current passing through the circuit produces

    Ans: 4

     

  19. When current passes through a metallic conductor, it temperature rises. This is due to

    Ans: 1

     

  20. If a parallel circuit is opened in the main line, the current

     

     Ans: 3


  1. A conductor of length L has carrying current I passing through it, when it is placed parallel to strong magnetic field. The force experienced by the conductor will be

    Ans: 4

     

  2. The force between two long parallel conductors is inversely proportional to

    Ans: 3

     

  3. In the left hand rule, forefinger always represents

    Ans: 1

     

  4. A wire carrying current is bent in the form of a circular loop. Then the magnetic field around each portion of the wire will be

    Ans: 1

     

  5. Cork Screw rule is used to find

     

     Ans: 1

  6. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be

     

     Ans: 2

  7. The field at any point on the axis of a current carrying coil will be

    Ans: 3

     

  8. Two straight parallel conductors carry equal currents in opposite direction. The force between them is

    Ans: 1

     

  9. While comparing magnetic field and electric circuits, the point of dissimilarity exists while considering

    Ans: 3

     

  10. A wire 2.5 m long is bent into a square. An current of 100 A flowing through the wire will produce a magnetizing force at the center of the square, equal to

     

     Ans: 2

  11. Magnetism of a magnet can be destroyed by

    Ans: 4

     

  12. The change of cross sectional area of conductor inmagnetic field will affect

    Ans: 3

     

  13. Substance having permeability less than the permeability of free space, are known as

     

     Ans: 4

  14. A point pole has a strength of 4π × 10-4 weber. The force in newtons on a point pole of 4π × 1.5 × 10-4weber placed at a distance of 10 cm from it will be

     

     Ans: 1

  15. Susceptibility is positive for

     

     Ans: 2

  16. Biot-Savart's law states the relation between magnetic intensity and

     

     Ans: 3

  17. The bar magnet has

     

     Ans: 1

  18. The magnetisation and applied field in ferromagnetic materials are related

    Ans: 2

     

  19. Temporary magnets are used in

    Ans: 1

     

  20. A degaussing is the process of

     

     Ans: 1

  1. Almost the entire mass of an atom is concentrated in the

    Ans:  4

     

  2. All ions of an element have the same

    Ans:  4

     

  3. The mass of the atom is determined by

    Ans:  3

     

  4. The absolute charge of an electron is

    Ans:  1

     

  5. The fixed circular paths around the nucleus are called

    Ans:  1


  6. According to the Bohr model, an electron gains or losses energy only by

    Ans:  2

     

  7. The number of rings in the Bohr model of any element is determined by what?

     

     Ans:  3

  8. How many valence electrons would be found in an atom with the atomic number of 51?

    Ans:  1

     

  9. The Bohr model of the atom

     

     Ans:  1

  10. Maximum number of electrons in a sub-shell with l = 3 and n = 4 is

     

     Ans:  2

  11. Which of the following statements is not part of Dalton's atomic theory?

     

     Ans:  4

  12. Atoms with fewer than 4 valence electrons are

     

     Ans:  3

  13. Atoms have no electric charge because they

    Ans:  4

     

  14. Two different isotopes of an element have different

    Ans:  1

     

  15. What is the mass number of an element that has 19 protons, 19 electrons, and 20 neutrons?

    Ans:  2

     

  16. Which of the following statements is not true?

     

     Ans:  3

  17. The drawback of Dalton's atomic structure is that, it says

     

     Ans:  1

  18. The electron configuration of copper is

    Ans:  2

     

  19. Silicon has

    Ans:  1

     

  20. The electron configuration of sulfur atom is

     

     Ans:  1

  1. The electron is lighter than a proton by a factor of about

    Ans: 3

     

  2. The charge of an electron is

    Ans: 1

     

  3. The mass of a proton is

    Ans; 2

     

  4. The mass of a neutron of atom is

    Ans: 1

     

  5. In Bohr’s model of atomic structure, the nucleus consists of

    Ans: 3

  1. The atomic radius in case of face centered cubic lattice is

    Ans: 2

     

  2. The materials which exhibit the same elastic properties in all directions are called

    Ans: 1

     

  3. Which of the following is the heaviest?

    Ans: 1

     

  4. Germanium has

    Ans: 2

     

  5. Energy gap of conductor is

    Ans: 2

     

  6. Energy gap of semiconductor is approx

    Ans:1