Many important questions are formed in competitive exams like CUET, JEE, NEET, and boards from Class 12 Physics Unit 3. Below, we have provided Important Questions from Class 12 Physics Unit 3 Magnetic Effects of Current and Magnetism for your JEE Mains 2023 preparation. You can check it here for revision purposes.
Latest:Â Electrostatics Class 12 JEE Questions and Answers
Electrostatics Class 12 JEE Mains Questions and Answers
We’ve compiled a list of important questions about the Magnetic Effects of Current and Magnetism physics class 12 unit 3 that you should not miss while studying for your JEE Main Exams.
Q.1. A straight wire of length π2 metre carrying a current of 2 A and the magnetic field due to it is measured at a point distant 1 cm from it. If the wire were bent into a circle and were to carry the same current as before, the ratio of the magnetic field at its centre to that obtained in the first case would be
(a) 50: 1 (b) 1: 50
(c) 100: 1 (d) 1: 100
A.1. (b)
Explanation:
Q.2. A bar magnet has a magnetic moment equal to 5 × 10–5 Wb m. It is suspended in a magnetic field which has a magnetic induction B equal to 8p × 10–4 T. The magnet vibrates with a period of vibration equal to 15 s. The moment of inertia of magnet is
(a) 4.54 × 104 kg m2 (b) 4.54 × 10–5 kg m2
(c) 4.54 × 10–4 kg m2 (d) 4.54 × 105 kg m2
A.2. (d)
Q.3.  In a hydrogen atom, the electrons moves in a circular orbit of radius 0.5 Å, about the nucleus. What is the magnetic induction produced at the centre of the orbit, if the electrons make 6.25 × 1015 rev per sec? [e = 1.6 × 10–19 C]
(a) 6.28 Wb m–2 (b) 9 Wb m–2
(c) 12.56 Wb m–2 (d) 15 Wb m–2
A.3. (c)
Explanation:
Q.4. There is a uniform electric field of strength 103 Vm–1 along the y-axis. A body of mass 1 g and charge 10–6 C is projected into the field from the origin along the positive x-axis with a velocity of 10 ms–1. Its speed (in ms–1) after 10 s will be (negative gravitation)
(a) 10 (b) 5√2 (c) 10√2 (d) 20
A.4. (c)
Explanation:
Q.5. A solenoid of length 0.4 m and having 500 turns of wire carries a current of 3.0 A. A thin coil having 10 turns of wire and of radius 0.01 m carries a current of 0.04 A. What is the torque required to hold the coil in the middle of the solenoid with its axis perpendicular to the axis of the solenoid ? (Use π2 = 10)
(a) 6 × 106 N m (b) 6 × 10–6 N m
(c) 7.5 × 10–6 N m (d) 4.2 × 10–6 N m
A.5. (b)
Explanation:
Q.6.  A B and C are parallel conductors of equal lengths carrying currents I, I and 2I respectively. Distance between A and B is x. Distance between B and C is also x. F1 is the force exerted by B on A. F2 is the force exerted by conductor C on A. Choose the correct answer.
(a) F1 = 2F2 (b) F2 = 2F1
(c) F1 = F2 (d) F1 = –F2
A.6. (d)
Explanation:
Q.7. A current-carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon
(a) area of loop (b) no. of turns in loop
(c) shape of loop (d) strength of current and magnetic field
A.7. (c)
Q.8. A coil of N turns and radis R carries a current I. it is unwound and rewound to make another coil of radius R/2, current remaining the same. What is the ratio of the magnetic moments of the new coil and the original coil?
(a) 1 : 1 (b) 1 : 2 (c) 2 : 1 (d) 1 : 3
A.8. (b)
Explanation:
Q.9. The magnetic susceptibility of a paramagnetic material at –73°C is 0.0075 and its value at –173°C will be
(a) 0.0030 (b) 0.0075
(c) 0.0045 (d) 0.015
A.9. (d)
Explanation:
Q.10. A long straight wire of radius R carries a current I. The current is uniformly distributed across its cross section. What is the ratio of the magnetic fields at distances of R/2 and 2R from its axis?
(a) 1/2 (b) 1 (c) 2 (d) 4
A.10. (b)
Explanation:
Best JEE Books Recommended by JEE Toppers
Check out some of the best JEE Books recommended by JEE Toppers
- NCERT Textbook
One thing that is strongly recommended is that students prepare using NCERT textbooks. Toppers endorse NCERT as the finest book for JEE Main. NCERT is the foundation for these exams since they cover everything and consist of enormous information. Each and every line of NCERT must be clear and embedded in your mind to know the concepts better.
 |
NCERT At Your Fingertips As we mentioned in the point above, each and every line of NCERT is important. NCERT At Your Fingertips is just the book for that purpose as it has over 100 MCQs from every line of NCERT and provides deep learning. It has MCQs pulled out from NCERT, NCERT Exemplar, previous years’ papers, practice papers, and model test papers. The book is a bestseller on every e-commerce platform and has been referred by teachers and lakhs of JEE toppers and aspirants as a jewel for JEE exam preparation. It has over 8000 5-star ratings and reviews on amazon alone. You can’t miss out on this book for extensive knowledge.
|
|
JEE Main Guide This series has separate books for physics, chemistry, and mathematics. MTG JEE Main Physics is the best book for JEE Main exam based on the latest pattern. The book comprises detailed theory with illustrations followed by Self-check MCQs. Chapter-wise MCQs and Numerical Value Questions with Hints and explanations are included for better understanding. |
 |
|
|
22 Years JEE Main Imagine having 21 years’ worth of experience for JEE Main? That is what you’ll get with this series of Physics, chemistry, and mathematics books. MTG’s 22 Years JEE Main Chapter-wise Topic-wise Solutions Physics is the best question bank having questions from the past 22 years of JEE Main Physics (2022-2013) & AIEEE (2012-2002) which are segregated Chapter-wise Topic-wise. |
|
NTA JEE Main This book for excelling in JEE MAIN has the real 104 online papers by NTA from 2019 to 2023. The book also provides 5 Mock test papers as per the latest pattern of JEE Main exam set by NTA in the end. MCQs and Numerical type questions are present in the book along with chapter-wise graphical analysis indicating the weightage of questions and topics. |
 |
|
|
JEE Champion JEE Champion is a book designed for JEE aspirants to prepare better with the knowledge of topic importance within a chapter. It familiarizes all the JEE aspirants with a wide variety of questions frequently asked in various engineering entrance exams. It covers 10 years of questions for all the major engineering exams. Students can understand the changing pattern of questions asked and can gain mastery over questions asked during exams.
|
|
46 Years JEE Advanced • 46 years of IIT-JEE/ JEE Advanced previous year questions |
 |
|
|
46+22 Years Chapterwise Topicwise Solutions • 46 Previous Years’ Papers of JEE Advanced/IIT JEE |
