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# NCERT Exemplar Class 12 Physics Chapter 6 Solutions: Electromagnetic Induction

NCERT Exemplar Class 12 Physics Solutions Chapter 6 is based on the concepts of Electromagnetic Induction. Covering major topics, laws, and formulae, the questions in this chapter would gear you for the CBSE Board exams as well as equip you with taking up competitive engineering and medical exams. The key topics discussed in this chapter of NCERT Exemplar Class 12 Physics are Faraday’s law of Electromagnetism and basics of Electricity and Magnetism, Magnetic Flux and Formulas on that, Lenz’s law, Inductance, Motional Electromotive Force and Formula around it, Eddy currents and its applications, and AC generator.

To Solve Exemplar Problems of NCERT Class 12 Physics students need to solve a total of 32 questions divided into 5 sections, which cover the topic extensively. The questions in different sections are objective type (MCQ) where MCQ1 has only one right answer while MCQ2 has one or more than one correct answer, very short answers, short answers, and long answers.

Our goal is to provide solutions to all the problems clearly and concisely which helps students understand the concepts and clarify all their doubts. Our subject matter experts have a thorough knowledge of each and every aspect of this topic where they enable students to memorize the formula around all the laws in an easy manner.

## Important Topics for NCERT Science Exemplar Solutions Class 12 Chapter 6

• Basics of electricity and magnetism – Magnetic field is created when an electric charge moves and vice versa i.e. a magnetic field induces motion in electric charge thereby producing an electric current.
• Magnetic fluxThe number of magnetic field lines that are crossing a surface and are perpendicular to it is the magnetic flux through that surface.

ϕ = M.A cos θ

Here M – magnetic field

A – area of the surface

θ  – the angle between the magnetic field and the area vector

• Faraday’s law of electromagnetism: Based on these fundamentals, Faraday and Henry carried out a long series of experiment from which 2 laws of electromagnetic induction came out:
• First law – If the magnetic field inside a conductor varies, it induces electromotive force and in a closed circuit conductor, a current is induced.
• Second law – Quantification of EMF – The magnitude of EMF induced in the circuit is equal to the rate at which magnetic flux changes with time within the circuit:

ε =  N (dϕ/dt)

Here ε – Electromotive force

Φ – Magnetic flux

t – Time

N – number of turns in the closed coil

• Lenz’s law and conservation of energy – This law states that the current induced in a closed conductor with a magnetic field inside always tends to oppose the cause of this induced current. So when an N-pole of a bar magnet is pushed towards a coil, a current is induced in the coil which repulses the bar magnet and extra work is required to keep moving the bar magnet towards the coil. This extra work is converted into electrical energy and dissipated as heat.

ε = ‒ N (dϕ/dt)

The negative sign shows that the current induced flows in the opposite direction of the cause of the change

• Motional EMF: The emf induced when a conductor across a magnetic field is called motional EMF and given by:

E = -vLM

Here M – magnetic field

L – Length of the conductor

v – Velocity with which the conductor is moving

• Eddy Currents – Eddy currents are based on the circular electric currents within conductive material like a filament. Since such currents produce heat losses they have applications in induction heating, welding, etc.

P = Cef2Mx2t2

Here P – Path of the eddy current

Ce – A constant which is dependant on the size of the material and    inversely proportional to its resistivity

f – frequency of the source of excitation

Mx – Highest value of the magnetic field

t – thickness of the material

• AC Generator – AC generators are built on the principles of electromagnetic induction that says that an alternating voltage can occur when a coil rotates in a magnetic field or a magnetic field rotates within a stationary coil. The voltage magnitude depends on the number of turns in the coil, the strength of the magnetic field and the speed at which either the coil or the field rotates.

## Discussion of Exercises of NCERT Exemplar Class 12 Physics Solutions Chapter 6

1. The first set of questions, MCQ1, is objective type questions with a single correct answer. It has 6 questions. They brush up topics like calculation of magnetic flux, laws of Faraday and Lenz.
2. The second set of questions is MCQ2, which are again objective type questions where there may be more than 1 correct answer and you must choose all the correct answers for the given problem statement. It has 3 questions based on eddy currents, EMF concepts, mutual inductance, and self-inductance.
3. The third set of questions requires very short type answers which touch areas like magnetic flux and its variation with time, Lenz’s law, and eddy currents. It has 6 questions.
4. The fourth set of questions requires short type answers where you need to apply Faraday’s laws, magnetic flux equations, and motional EMF to solve the 5 questions provided.
5. The fifth set of questions involve long answers and test your expertise on motional EMF, the formula of magnetic flux, Faraday’s law along with integration fundamentals to solve the 11 questions presented.
6. The problems in the NCERT Exemplar Class 12 book give students a variety of problems on all the topics which are very important from the point of view of CBSE exams and many competitive exams also. The NCERT Exemplar Problems for all chapters of CBSE Class 12 Physics is an invaluable resource in getting a clear understanding of this subject.

## Why Use NCERT Science Exemplar Solutions Class 12 Chapter 6 by Instasolv?

Physics can be a daunting topic for students of class 12 as it has many advanced concepts to understand. You can find many NCERT Exemplar Problems with Solutions but what you need is a complete solution that explains each step of the problem in detail.

The Instasolv team of Subject Matter Experts does a fantastic job of breaking down the most complex problems in simple steps.  With proper explanation which clears all doubts, Instasolv is a great resource for students which are also free of cost.

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