Assertion Reason Physics Chapter 6 Electromagnetic Induction

Questions of Assertion Reason of Physics Chapter 6 Electromagnetic Induction CBSE Class 12 are very simple to understand as this chapter deals with Electromagnetic Induction. To solve assertion reason type questions of Physics, a deeper understanding of concept about The Experiments of Faraday and Henry, Magnetic Flux, Faraday’s Law of Induction, Lenz’s Law and Conservation of Energy, Motional Electromotive Force, Inductance and AC Generator is required. In order to help the student in solving Assertion Reason type of questions, detailed process is explained.

How to solve Assertion Reason Type Questions?
In Assertion-Reason type of question, two statements are given, first is Assertion and second is called Reason. Student must have to think critically about both the statements in Assertion Reason Questions, since it combines multiple choice questions and true/false type of questions which requires a higher level of understanding.

How many types are there of Assertion Reason Type Questions?
Assertion-Reason type of questions can be asked either with four MCQ options or with five MCQ options. First four options are same in both the cases only one more options is being provided i.e. last one. One extra option increases the difficulty level of the questions.

In assertion reason type of questions, all 4 or 5 options are same for each question, which are as:

(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.

Then a question haunts in every student’s mind, which option is correct and when?
This can be understood clearly with the following table:

Assertion (A)Reason (R)MCQ Options (Fixed for all questions)
If TrueTrue(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
If TrueTrue(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
If TrueFalse(c) Assertion (A) is true but reason (R) is false.
If FalseTrue(d) Assertion (A) is false but reason (R) is true.
If FalseFalse(e) Both Assertion and Reason are false.

Now, lets practice some Assertion Reason Questions of Physics: Chapter 6 Electromagnetic Induction

Read instructions carefully before answering the questions.

For question given below, two statements are given- one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

(a) Both A and R are true and R is correct explanation of the assertion.
(b) Both A and R are true but R is not the correct explanation of the assertion.
(c) A is true but R is false.
(d) A is false but R is true.

Question.1.
Assertion: Induced emf will always occur whenever there is change in magnetic flux.
Reason: Current always induces whenever there is change in magnetic flux.

Ans.1. (c)
Emf will always induces whenever, there is change in magnetic flux. The current will induced only in closed loop.

Question.2.
Assertion: Faraday’s laws are consequence of conservation of energy.
Reason: In a purely resistive ac circuit, the current legs behind the emf in phase.

Ans.2. (c)
In purely resistive circuit, the current and emf are in the same phase.

Question.3.
Assertion: Only a change in magnetic flux will maintain an induced current in the coil.
Reason: The presence of large magnetic flux through a coil maintain a current in the coil of the circuit is continuous.

Ans.3. (c)
A is true but R is false.

Question.4.
Assertion: Lenz’s law violates the principle of conservation of energy.
Reason: Induced emf always opposes the change in magnetic flux responsible for its production.

Ans.4. (a)
Lenz’s law (that the direction of induced emf is always such as to oppose the change that cause it) is direct consequence of the law of conservation of energy.

Question.5.
Assertion: An induced current has a direction such that the magnetic field due to the current opposes the change in the magnetic flux that induces the current.
Reason: Above statement is in accordance with conservation of energy.

Ans.5. (b)
Both A and R are true but R is not the correct explanation of the assertion.

Question.6.
Assertion: Acceleration of a magnet falling through a long solenoid decreases.
Reason: The induced current produced in a circuit always flow in such direction that it opposes the change to the cause that produced it.

Ans.6. (a)
Both A and R are true and R is correct explanation of the assertion.

Question.7.
Assertion: Figure shows a horizontal solenoid connected to a battery and a switch. A copper ring is placed on a smooth surface, the axis of the ring being horizontal. As the switch is closed, the ring will move away from the solenoid.
Reason: Induced emf in the ring, e=-\frac{d\phi}{dt} .

Ans.7. (a)
When switch is closed , the magnetic flux through the ring will increase and so ring will move away form the solenoid so as to compensate this flux. This is according to Lenz’s law.

Question.8.
Assertion: An emf can be induced by moving a conductor in a magnetic field.
Reason: An emf can be induced by changing the magnetic field.

Ans.8. (b)
In both the cases, the magnetic flux will change, and so there is an induced current.

Question.9.
Assertion: Figure shows a metallic conductor moving in magnetic field. The induced emf across its ends is zero.
Reason: The induced emf across the ends of a conductor is given by e = Bvℓ sinθ.

Ans.9. (a)
Both A and R are true and R is correct explanation of the assertion.

Question.10.
Assertion: Eddy currents are produced in any metallic conductor when magnetic flux is changed around it.
Reason: Electric potential determines the flow of charge.

Ans.10. (b)
Both the statements are independently correct.

Question.11.
Assertion: An induced emf appears in any coil in which the current is changing.
Reason: Self induction phenomenon obeys Faraday’s law of induction.

Ans.11. (b)
Both A and R are true but R is not the correct explanation of the assertion.

Question.12.
Assertion: When number of turns in a coil is doubled, coefficient of selfinductance of the coil becomes 4 times.
Reason: This is because L\alpha N^{2} .

Ans.12.(b)
Both A and R are true but R is not the correct explanation of the assertion.

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