Electromagnetic Induction MCQ

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Electromagnetic Induction MCQ are formed as per the latest exam pattern. Chapter 6 Electromagnetic Induction MCQs include concepts of the magnetic field, Faraday’s laws, conductor, and electromotive force.

Electromagnetic induction is a process by which electromotive force is generated, due to the interaction between the conductor and a magnetic coil. The force is generated when at least one of them is in motion, either the conductor or the magnetic field. According to Faraday, an electromotive force will be generated, if a stationary magnet is kept in a moving magnetic field, or if the magnetic field is kept constant, and the conductor is moved. The formula to determine the electromagnetic induction is:

e = N × dΦ / dt

Here,

  • e = the induced voltage (volts)
  • N = number of circular twists and turns in the coil
  • Φ = magnetic flux (Webers)
  • t = time (seconds)

Read More: NCERT Solutions for Class 12 Physics Chapter 6 Electromagnetic Induction


Electromagnetic Induction MCQ

Question 1: The emf induced in the circuit when the magnetic flux associated with an electric circuit changes is known as:

  1. electromagnetic induction
  2. lenz’s law
  3. hysteresis loss
  4. Kirchhoff laws

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Answer: (a) electromagnetic induction

Explanation: Electromagnetic induction is a process by which electromotive force is generated, due to the interaction between the conductor and a magnetic coil. The force is generated when at least one of them is in motion, either the conductor or the magnetic field.

Question 2: The EMI induced is independent of which of the following factors:

  1. change of flux
  2. time.
  3. resistance of the coil
  4. None of these

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Answer: (b) Time

Explanation: The electromagnetic induction induced is proportional to the number of turns/coils present in the wire, which affects the resistance in the coil. Moreover, it is also dependent on the change in the magnetic field, and this alters the magnetic flux. Thus the only factor which doesn't alter the EMI is time.

Question 3: Magnets produce induced e.m.f. when inserted into coils. The strength of the induced e.m.f. is independent of the:

  1. the strength of the magnet
  2. number of turns of coil
  3. the resistance of the wire in the coil
  4. speed with which the magnet is moved

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Answer: (c) The resistance of the wire in the coil

Explanation: The electromotive force is generated when either the coil or the magnet is in motion with respect to each other. Here the strength of the magnet, or the number of coils alters the EMF and not the resistance of the wire of the coil.

Question 4: The electromagnetic induction is ____ according to the Faraday's law of electromagnetic induction:

  1. an electric field is produced by time varying magnetic flux.
  2. a magnetic field is produced by time varying electric flux.
  3. a magnetic field is associated with a moving charge.
  4. None of these

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Answer: (a) It is an electric field produced by time varying magnetic flux

Explanation: Faraday's law clearly states that the EMI is the electric field produced by a time varying magnetic flux. It is a law, and cannot be changed.

Question 5: The induced e.m.f. of a moving conductor coil can be measured using the following law:

  1. Lenz's law
  2. Faraday’s law
  3. Coulomb’s law
  4. Ampere’s law

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Answer: (b) Faraday’s law

Explanation: Faraday's Law is used to measure the induced e.m.f of the moving conductor coil. Lenz's law is used to measure the polarity of induced e.m.f. Coulomb's Law determines the force between two stationary electrically charged particles. Ampere's law correlates with the magnetic field induced in a coil.

Question 6: When an insulated wire coil is connected to a battery, the pointer of the galvanometer is deflected due to:

  1. the induced current produced
  2. the coil acts like a magnet
  3. the number of turns in the coil of the galvanometer is changed
  4. None of these

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Answer: (a) The induced current produced

Explanation: A galvanometer measures the amount of current flowing through the circuit. In a current flowing conductor connected to a battery, the pointer of the galvanometer fluctuates and points to the amount of current flowing. Thus a galvanometer measures the amount of induced current in the circuit.

Question 7: Polarity of the induced emf is determined by:

  1. Ampere’s circuital law
  2. Biot–Savart law
  3. Lenz’s law
  4. Fleming’s right-hand rule

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Answer: (c) Lenz’s law

Explanation: Lenz's law is used to measure the polarity of induced e.m.f. Ampere's law correlates with the magnetic field induced in a coil. Biot–Savart law describes the magnetic field generated by a constant electric current. Fleming's right-hand rule gives the estimate that in which direction the current will flow.

Question 8: A coil's self-inductance is a measure of its:

  1. electrical inertia
  2. electrical friction
  3. induced e.m.f.
  4. induced current

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Answer: (a) electrical inertia

Explanation: Self-inductance is a property of a coil. This maintains the magnetic flux generated in the coil and prevents any changes to it. Since it avoids any changes it's known as inertia, and since electricity is involved, thus electrical inertia.

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Question 9: In resistance boxes, the coils are made from doubled-insulated wires to eliminate the effect of:

  1. heating
  2. magnetism
  3. pressure
  4. self-induced e.m.f.

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Answer: (d) self induced e.m.f.

Explanation: In resistance boxes, the coils are made from double insulated wires. In double insulated wires, the wire is double coiled on itself. Because of double coiling, there is an equal and opposite current flowing in each section of the coil. They both nullify each other, therefore, the coil has no net magnetic field and hence, no net induced e.m.f. Thus, it is done to minimize the self-induced emf of coils.

Question 10: A series connection of two pure inductors each of self-inductance L yields a net inductance of:

  1. L
  2. 2 L
  3. L/2
  4. L/4

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Answer: (b) 2L

Explanation: We can calculate the total inductance of a series of inductors by substituting the values in the equation: Leq = L1 + L2. If we substitute these values, then we get Leq = L.


Previous Year Questions

Questions on Lenz Law 

  1. Lenz’s law is consequence of the law of conservation of….. [UPSEE 2019]
  2. The magnetic field is increasing at a constant rate. The directions of induced current in wires AB and CD  are…. [VITEEE 2019]
  3. the circular loop of wire is moved with velocity towards the infinite current carrying wire…… [VITEEE 2016]
  4. Two identical coaxial coils P and Q  carrying equal amount of current in the same direction are brought nearer. The current in...[KEAM]
  5. The polarity of induced emf is given by….[KEAM]

Questions on Electromagnetic Induction

  1.  If a transformer of an audio amplifier has output impedance 8000 0 and the speaker has input impedance…...[JCECE 2005]
  2. A conducting loop in the shape of a right angled isosceles triangle of height 10cm10cm is kept such that the 90 vertex is…..[JEE Advance 2016]
  3. A 10m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0ms−1……. [ JEE Main 2019]
  4. If a current of 2.0A2.0A flows through the smaller loop, then the flux linked with bigger loop is…… [JEE Main 2013]
  5. A coil of cross-sectional area A having n turns is placed in a uniform magnetic field B….. [JEE Main 21018]
  6. A copper rod of mass m slides under gravity on two smooth parallel rails, with separation ll and set at an angle of θ with the horizontal….. [JEE Main 2018]
  7. A copper wire is wound on a wooden frame, whose shape is that of an equilateral…. [JEE Main 2019]
  8. A metallic rod of length ll is tied to a string of length 2l and made to rotate with angular speed…. [JEE Main 2013]
  9. A square frame of side 10 cm and a long straight wire carrying current 1 A are in the plane of the paper…. [JEE Main 2014]
  10. If the rod makes n rotations per second, then the time averaged magnetic moment of the rod is… [JEE Main 2019]
  11. Figure shows a circular area of radius R where a uniform magnetic field….
  12. In a coil of resistance 100Ω , a current is induced by changing the magnetic flux through it….. [JEE Main 2017]
  13. When current in a coil changes from 5A  to 2A…. [JEE Main 2015]

Questions on Faradays laws of induction

  1. Two identical circular coils A and B are kept on a horizontal tube side by side without touching each other…. [KCET 2013]
  2. The magnetic flux through a circuit of resistance RR changes by an amount….[NEET 2004]
  3. A conducting loop in the shape of a right angled isosceles triangle of height...[JEE Advance 2016]
  4. If a transformer of an audio amplifier has output impedance…..[JCECE]

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CBSE CLASS XII Related Questions

  • 1.
    A battery of emf \( E \) and internal resistance \( r \) is connected to a rheostat. When a current of 2A is drawn from the battery, the potential difference across the rheostat is 5V. The potential difference becomes 4V when a current of 4A is drawn from the battery. Calculate the value of \( E \) and \( r \).


      • 2.
        In a circular loop of radius \( R \), current \( I \) enters at point \( A \) and exits at point \( B \), as shown in the figure. The value of the magnetic field at the centre \( O \) of the loop is:

          • \( \dfrac{\mu_0 I}{R} \)
          • zero
          • \( \dfrac{\mu_0 I}{2R} \)
          • \( \dfrac{\mu_0 I}{4R} \)

        • 3.
          A coil of an AC generator, having 100 turns and area 0.1 m² each, rotates at half a rotation per second in a magnetic field of 0.02 T. The maximum emf generated in the coil is:

            • 0.31 V
            • 0.20 V
            • 0.63 V
            • 0.10 V

          • 4.
            A current carrying circular loop of area A produces a magnetic field \( B \) at its centre. Show that the magnetic moment of the loop is \( \frac{2BA}{\mu_0} \sqrt{\frac{A}{\pi}} \).


              • 5.
                A coil has 100 turns, each of area \( 0.05 \, \text{m}^2 \) and total resistance \( 1.5 \, \Omega \). It is inserted at an instant in a magnetic field of \( 90 \, \text{mT} \), with its axis parallel to the field. The charge induced in the coil at that instant is:

                  • \( 3.0 \, \text{mC} \)
                  • \( 0.30 \, \text{C} \)
                  • \( 0.45 \, \text{C} \)
                  • \( 1.5 \, \text{C} \)

                • 6.
                  A conductor of length \( l \) is connected across an ideal cell of emf E. Keeping the cell connected, the length of the conductor is increased to \( 2l \) by gradually stretching it. If R and \( R' \) are initial and final values of resistance and \( v_d \) and \( v_d' \) are initial and final values of drift velocity, find the relation between:
                  \( R' \) and \( R \)
                  \( R' = 4R \)

                    CBSE CLASS XII Previous Year Papers

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