Class 12 Physics MCQ – Faraday’s Law of Induction

This set of Class 12 Physics Chapter 6 Multiple Choice Questions & Answers (MCQs) focuses on “Faraday’s Law of Induction”.

1. Which among the following is true about Faraday’s law of Induction?
a) An emf is induced in a conductor when it cuts the magnetic flux
b) An emf is induced in a conductor when it moves parallel to the magnetic field
c) An emf is induced in a conductor when it moves perpendicular to the magnetic field
d) An emf is induced in a conductor when it is just entering a magnetic field
View Answer

Answer: a
Explanation: According to Faraday’s law of electromagnetic induction, an emf is induced in a conductor when it cuts across the flux of a magnetic field. If the two ends of the conductor are connected to an outside circuit, the induced emf causes current to flow in the circuit.

2. What is proportional to the magnitude of the induced emf in the circuit?
a) Rate of change of current in the circuit
b) Rate of change of resistance offered
c) Rate of change of magnetic flux
d) Rate of change of voltage
View Answer

Answer: c
Explanation: The magnitude of induced emf is equal is equal to the time rate of change of magnetic flux. It is mathematically expressed as:
ε = \(\frac {-d\phi }{dt}\)
The negative sign indicates the direction of the emf induced. This is Faraday’s second law of electromagnetic induction.

3. Faraday’s laws are result of the conservation of which quantity?
a) Momentum
b) Energy
c) Charge
d) Magnetic field
View Answer

Answer: b
Explanation: Faraday’s laws are result of the conservation of energy. These laws are based on the conversion of electrical energy into mechanical energy. Mechanical energy can be converted into electrical energy such as in the example of a dynamo. In the same way, electrical energy can be converted into mechanical energy such as in the example of electric motor. Both of the above examples work on the principle of Faraday’s law.
advertisement
advertisement

4. The induced emf persists only as long as the change in magnetic flux continues.
a) True
b) False
View Answer

Answer: a
Explanation: According to Faraday’s first law, whenever the amount of magnetic flux linked with a circuit changes, an emf is induced in the circuit. This induced emf persists as long as he change in magnetic flux continues. Therefore, this is a true statement.

5. The magnetic flux in a closed circuit of resistance 20 Ω varies with time t as Φ = 4t3 + 2t2 – 15t + 3. Calculate the magnitude of induced emf at t = 1s.
a) 3 V
b) 4 V
c) 5 V
d) 6 V
View Answer

Answer: b
Explanation: Given: Resistance = 20 Ω; Φ = 4t3 + 2t2 – 15t + 3
Required equation ➔ ε = \(\frac {-dΦ}{dt}\)
ε=\(\frac {-d(4t^3 + 2t^2 – 15t + 3)}{dt}\) = -(12t2 + 4t – 15t + 3)
= -12 – 4 + 15 – 3 (Since t = 1s)
= 4 V
Therefore, the magnitude of induced emf is 4V.
Note: Join free Sanfoundry classes at Telegram or Youtube

Sanfoundry Global Education & Learning Series – Physics – Class 12.

To practice all chapters and topics of class 12 Physics, here is complete set of 1000+ Multiple Choice Questions and Answers.

advertisement

advertisement
advertisement
Subscribe to our Newsletters (Subject-wise). Participate in the Sanfoundry Certification contest to get free Certificate of Merit. Join our social networks below and stay updated with latest contests, videos, internships and jobs!

Youtube | Telegram | LinkedIn | Instagram | Facebook | Twitter | Pinterest
Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

Subscribe to his free Masterclasses at Youtube & discussions at Telegram SanfoundryClasses.