CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25: Chapter 3 Magnetic Effects of Current and Magnetism FREE PDF Download

CBSE 2024-25 Competency-Based Questions With Answers: The Central Baord of Secondary Education has officially released the practice question paper for the academic year 2024-25, for the classes 10th  and 12th. Competency-focused questions can be helpful for students to secure good marks while referring and practicing them. It will help students to get familiar with the style and format of questions which are expected to appear in the final examinations.

In this article we have provided specifically, for Class 12 Physics, Chapter 3 on Magnetic Effects of Current and Magnetism, competency-based questions designed to enhance understanding and application skills for the 2025 exams. Students can download the free PDF mentioned in the end of the article. 

CBSE Class 12 Physics Chapter 3 Competency-Based Questions

Question 1: Read the following points of comparison between electric and magnetic fields  carefully. 

i. Both Coulomb’s law and Biot‐ Savart’s laws follow inverse square law. 

ii. Both electric and magnetic field values depend upon the angle between the  displacement vector and the field source. 

iii. Electric  field  is  produced  by  a  scalar  source  whereas  magnetic  field  is  produced by a vector source. 

iv. The direction of the magnetic field is along the displacement vector joining  the  field  source  and  field  point.  On  the  other  hand,  the  electric  field  is  perpendicular to the plane containing the displacement vector joining the field  source and the field point. 

Identify the correct statements. 

1. only i and ii 
2. only iii and iv 
3. only ii and iv 
4. only i and iii 

Question 2: A deuteron and an alpha particle move with the same kinetic energy under the 

effect of identical magnetic fields. 

What will be the ratio of the radii of their paths followed? 

1. 1 
2. √2 
3. 1/2 
4. 2 

Question 3:  A  particle  of  charge  q  and  mass  m  projected  with  a  speed  v  into  a  uniform  magnetic field B undergoes circular motion under the effect of magnetic force.  Identify an INCORRECT statement.  

1. Both KE and PE of this charged particle remain constant. So no work is done by the magnetic field on it. 
2. An  identical  charged  particle  projected  at  an  angle  other  than  90o  with magnetic field B will undergo helical motion. 
3. Another charged particle of a different specific charge, projected with the same speed will still have the same angular frequency. 
4. An identical charged particle projected with double the speed in the same magnetic field will follow a circular path of larger circumference than the earlier one but with the same time period. 

Question 4:  A negatively charged particle moves with velocity v through a magnetic field B and experiences a magnetic force F. In  each  of  the  diagrams  below,  the  representation  of  magnetic  field  lines  is missing. 

Identify the probable direction of magnetic field lines in each case as Left, Right, 

Upwards or Downwards. 

1. i‐Right, ii‐Upwards, iii‐Upwards, iv‐Right 
2. i‐Left, ii‐Downwards, iii‐Downwards, iv‐Left 
3. i‐Downwards, ii‐Right, iii‐Upwards, iv‐Upwards 
4. i‐Left, ii‐Right, iii‐Upwards, iv‐ Downwards 

Question 5: Each of the diagrams represents magnetic field lines around a wire  carrying current I from different perspectives.  Identify which of the following representations are correct. 

1. only i and iv 
2. only ii and iii 
3. only i and iii 
4. only ii and iv 

Question 6:  A rod of insulating material of length 0.5 m carries a static charge of 1 C at one end. The rod is rotated in a vertical plane about a horizontal axis passing through the other end with an angular frequency of 10π rad/s. What is the magnetic field at the center of the circular path? 

1. 2π x 10^‐6 T 
2. 4π² x 10^‐6 T 
3. 0.4 x 10^‐7 T 
4. Zero 

Question 7:  A wire of length L carrying a current I can be turned into a circular coil of  N turns. For what turned value of N, will the magnetic moment of this current carrying 

coil be maximum? 

1. one 
2. 4πL 
3. infinite 
4. (Magnetic moment is a constant for a given L and is independent of N) 

Question 8:  Which of the following statements is INCORRECT for a magnetic dipole? 

1. A  freely  suspended  magnetic  dipole  in  a  uniform  magnetic  field  always turns to align parallel to the external magnetic field. 
2. A magnetic dipole that is free to move in a non‐uniform magnetic field can slide as well as rotate. 
3. The  torque  required  to  hold  a  freely  suspended  magnetic  dipole  is maximum when thedipole is perpendicular to the direction of the external magnetic field. 
4. A small angular displacement given to a magnetic dipole result in a simple harmonic motion about its original position, irrespective of its orientation  in a uniform magnetic field. 

Question 9:  Two blocks of different materials are placed in a uniform magnetic field B. The  magnetic field lines passing through the two blocks are represented as follows.

Identify  the   suitable   values   of   relative   permeability   μr   and   magnetic  susceptibility χ for the materials I and II. 

1. For I : μr > 1, χ < 0, For II : μr < 1, χ > 0 
2. For I : μr < 1, χ = 0, For II : μr > 1, χ = 0 
3. For I : μr = 0, χ = 1, For II : μr = 1, χ = 0 
4. For I : μr < 1, χ < 0, For II : μr > 1, χ > 0 

Qyestion 10:  An  electromagnet  is  a  current‐carrying  solenoid  with  a  core  as  a  magnetic  material. Given below are B‐H (net field Vs. magnetizing field) curves of three  different magnetic materials. 

Identify the most suitable magnetic material using their B‐H curves, that can be 

used for the purpose of an electromagnet core. 

1. I is better than II and III 
2. II is better than I and III 
3. III is better than I and II 
4. II and III are better than I 

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To access all the practice question of Physics Chapter 3 Magnetic Effects of Current and Magnetism, the complete FREE PDFs are attached here. Click on the 'Download PDF' to get the PDF.

CBSE Class 12 Physics Competency-Based Questions With Answer Key 2024-25

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• Create a Study Plan: Making study plan befor exam will beneficial for students. Break your syllabus into small sections as per your comfort level and allocate time for each subject based on its difficulty and your comfort level with it.
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• Use Quality Study Materials: Rely on NCERT or prescribed textbooks as they are usually the basis for board exams. Use additional reference books and guides for more in-depth understanding if necessary.
• Practice Past Papers: Practice last year board exam sample papers to get a feel for the types of questions asked and the exam format. Take timed mock tests to improve your speed and accuracy.
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• Regular Revision: Regularly revise what you've studied to brushup your memory. Make concise notes for quick revision of key points.
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By following these tips, you can improve your preparation for board exams and increase your chances of achieving your desired results.