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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:
- electromagnetic induction
- lenz’s law
- hysteresis loss
- 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:
- change of flux
- time.
- resistance of the coil
- 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:
- the strength of the magnet
- number of turns of coil
- the resistance of the wire in the coil
- 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:
- an electric field is produced by time varying magnetic flux.
- a magnetic field is produced by time varying electric flux.
- a magnetic field is associated with a moving charge.
- 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:
- Lenz's law
- Faraday’s law
- Coulomb’s law
- 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:
- the induced current produced
- the coil acts like a magnet
- the number of turns in the coil of the galvanometer is changed
- 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:
- Ampere’s circuital law
- Biot–Savart law
- Lenz’s law
- 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:
- electrical inertia
- electrical friction
- induced e.m.f.
- 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:
- heating
- magnetism
- pressure
- 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:
- L
- 2 L
- L/2
- 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
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