MCQs On Uses Of Transformer

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A transformer is a device which is used in the electrical industry for power transmission of electric energy from one electrical circuit to another circuit or multiple circuits.

The video below explains this:

Transformer Detailed Video Explanation:


MCQs On Uses Of Transformer

Ques 1. The core of a transformer is laminated to (1 Mark)

  1. Reduce hysteresis loss
  2. Reduce copper losses
  3. Reduce eddy's current losses
  4. All of the above

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Ans. c. Reduce eddy's current losses

Explanation: The core of a transformer is laminated to reduce eddy's current losses.

Ques 2. In a transformer, energy is conveyed from primary to secondary through (1 Mark)

  1. Air
  2. Flux
  3. Cooling coil
  4. All of the above

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Ans. b. Flux

Explanation: Energy in a transformer is conveyed through flux from primary to secondary.

Ques 3. The path of magnetic flux in a transformer should have (1 Mark)

  1. High resistance 
  2. Low resistance 
  3. High reluctance 
  4. Low reluctance

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Ans. d. Low reluctance

Explanation: The path of magnetic flux in a transformer should have a low reluctance

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Ques 4. The no-load on a transformer is carried out to determine the (1 Mark)

  1. Magnetising current
  2. Magnetising current and loss
  3. Copper loss
  4. The efficiency of a transformer

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Ans. b. Magnetising current and loss

Explanation: The no-load on a transformer is carried out to determine the magnetising current and loss

Ques 5. The degree of mechanical vibrations produced by the laminations of a transformer depends on (1 Mark)

  1. Size of a laminations
  2. Gauge of laminations
  3. Tightness of clamping
  4. All of the above

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Ans. d. All of the above

Explanation: The degree of mechanical vibrations produced by the laminations of a transformer depends on the size of a lamination, gauge of laminations and tightness of clamping.

Ques 6. The dielectric strength of transformer oil is expected to be (1 Mark)

  1. 100 kV
  2. 1kV
  3. 33kV
  4. 330kV

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Ans. c. 33kV

Explanation: The dielectric strength of transformer oil is expected to be 33kV.

Ques 7. The efficiency of a transformer is maximized when (1 Mark)

  1. Hysteresis losses = eddy current losses
  2. Copper losses = iron losses
  3. Copper losses = hysteresis losses
  4. Eddy current losses = copper losses

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Ans. Copper losses = iron losses

Explanation: When copper losses = iron losses, the efficiency of a transformer is maximized.

Ques 8. No-load current in a transformer (1 Mark)

  1. Leads the voltage by about 75°
  2. Lags behind the voltage by about 75°
  3. Leads the voltage by about 15°
  4. Lags behind the voltage by about 15°

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Ans. b. Lags behind the voltage by about 75°

Explanation: No-load current in a transformer lags behind the voltage by about 75°.

Ques 9. Which of the following is not a part of the transformer installation (1 Mark)

  1. Breather
  2. Exciter
  3. Conservator
  4. Buchholz relay

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Ans. b. exciter

Explanation: Exciter is not used while installing transformer.

Ques 10. The purpose of providing iron ore in a transformer is to (1 Mark)

  1. Reduce hysteresis loss
  2. Reduce eddy current loss
  3. Provide support to windings
  4. Reduce the reluctance of the magnetic path

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Ans. d. Reduce the reluctance of the magnetic path

Explanation: The purpose of providing iron ore in a transformer is to reduce the reluctance of the magnetic path.

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CBSE CLASS XII Related Questions

  • 1.
    A charged particle $+q$ in an electric field $\vec{E}$ experiences a force in the direction of the electric field. As a result, its kinetic energy changes. Similarly, the charged particle also experiences a force when it moves in a magnetic field $\vec{B}$. But this magnetic force is perpendicular to both velocity $\vec{v}$ of the charged particle and the magnetic field $\vec{B}$, so it cannot change the kinetic energy of the charged particle. Consider two charged particles 1 and 2 of masses $m$ and $\frac{m}{2}$ having charges $-q$ and $+2q$ respectively. They are accelerated from rest through the same potential difference $V$ and acquire kinetic energy $K_1$ and $K_2$. Then they enter in a region of uniform magnetic field $\vec{B}$ perpendicular to their velocities.


      • 2.
        A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of the voltmeter and the ammeter by using the rheostat.


          • 3.
            This ‘average velocity’ is found be few mm/s for currents in range of a few amperes. How then is current established almost the instant a circuit is closed ?


              • 4.
                Capacitors are manufactured with certain standard capacitances and working voltages. However, these standard values may not be the ones that are actually needed in a particular application. Two or more capacitors can be grouped in series or in parallel to achieve desired capacitance and voltage. When connected in series, the total capacitance decreases while the voltage rating increases, whereas in parallel connections, the total capacitance increases and maintains the same voltage rating. A capacitor stores energy in the electric field between its plates and stored energy is proportional to the square of the voltage and capacitance $U = \frac{1}{2}CV^2$, where symbols have their usual meanings.
                Two capacitors, one of $3 \ \mu$F and the other of $6 \ \mu$F, are connected in series in the circuit as shown in the figure, for a long time. }


                  • 5.
                    Two metal spheres of radii $r_1$ and $r_2$ ($> r_1$) having charges $q_1$ and $q_2$ respectively kept in air, are brought in contact. Which of the following statements is not correct ?

                      • The total charge of the two spheres is conserved.
                      • Both spheres attain the same potential.
                      • The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2)}{(r_1 + r_2)}$
                      • The final potential of the system equals $\frac{1}{4\pi\epsilon_0} \frac{(q_1 + q_2) (r_1 + r_2)}{r_1 r_2}$

                    • 6.
                      Read the following paragraph and answer the questions that follow.
                      In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.

                        CBSE CLASS XII Previous Year Papers

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