# WBJEE: Important Questions and Preparation Tips – Electromagnetic Induction

Nov 20, 2017 11:47 IST
WBJEE 2018: Electromagnetic Induction

In this article, we bring to you concise chapter notes of chapter Electromagnetic Induction based on the latest syllabus for WBJEE Entrance Examination 2018. These notes are in very concise form and can be used for quick revision before the examination.

These chapter notes are prepared by Subject Experts after the detailed analysis of some previous year papers of WBJEE Examination.

These chapter notes consist all important topics related to chapter Electromagnetic Induction like magnetic flux, Faraday’s law of induction, Lenz’s law, conservation of energy, motional and rotational electromotive force, inductance etc.

These chapter notes include important concepts, formulae and some previous year solved questions.

West Bengal Joint Entrance Examination (WBJEE) is a state level common entrance test organized by West Bengal Joint Entrance Examinations Board for admission to the Undergraduate Level Engineering and Medical Courses through a common entrance test in the State of West Bengal

Important Concepts:

Some previous years solved questions are given below:

Question 1:

A conducting loop in the form of a circle is placed in a uniform magnetic field with its plane perpendicular to the direction of the field. An e.m.f. will be induced in the loop if

(A) it is translated parallel to itself.

(B) it is rotated about one of its diameters.

(C) it is rotated about its own axis which is parallel to the field.

(D) the loop is deformed from the original shape.

Solution 1:

Emf will be induced in the loop only when flux changes. Now, if the loop is translated parallel to itself then there is no flux change. Hence option A is not correct.

If the loop is rotated about one of its diameters then the flux passing through loop changes so, B is correct option.

If the axis is parallel to field then again there will be no change in flux and hence no emf will be induced in the loop.

If the loop is deformed then obviously its area will change and hence the flux flowing through it will also change.

Hence, the correct options are (B) and (D).

Important Questions and Preparation Tips – Magnetism

Question 2:

A straight conductor 0.1m long moves in a uniform magnetic field 0.1T. The velocity of the conductor is 15 m/s and is directed perpendicular to the field. The e.m.f. induced between the two ends of the conductor is

(A) 0.10 V

(B) 0.15 V

(C) 1.50 V

(D) 15.00 V

Solution 2:

The e.m.f. induced between the two ends of the conductor is given as:

E = Blv = 0.1×0.1×15 = 0.15V

Hence, the correct option is (B).

Question 3:

An electron in a circular orbit of radius .05 nm performs 1016 revolutions per second. The magnetic moment due to this rotation of electron is (in Am2)

(A) 2.16 × 10–23

(B) 3.21 × 10–22

(C) 3.21 × 10–24

(D) 1.26 × 10–23

Solution 3:

Let the magnetic moment be M.

Hence, the correct option is (D).

Important Questions and Preparation Tips – Electrostatics

Question 4:

Solution 4:

Hence, the correct option is (C).

How to guess the correct option in IIT JEE 2017 Examination: Must know these 7 tips

JEE Advanced Syllabus 2018 – complete syllabus for Physics, Chemistry and Mathematics

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