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Moving Charges and Magnetism

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Class 12 Physics Chapter 4
Moving Charges and Magnetism
Important Questions

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Mastering a variety of question formats on ‘Current Electricity’ is essential for class 12 syllabus. These curated class 12 physics current electricity important questions and answers serve as a valuable tool for comprehensive preparation. They offer students an opportunity to tackle uncertainties, bolster confidence, and refine their problem-solving skills. By delving into these current electricity class 12 important questions students can strengthen their understanding of the most significant concepts within the topic. These current electricity imp questions aim to solidify knowledge on current electricity, ensuring students approach the exam with assurance and proficiency.”

Introduction

Exploring ‘Moving Charges and Magnetism’ unveils a captivating chapter in Class 12 Physics, delving into the mesmerizing world of electromagnetic phenomena and their real-world applications. This section encompasses fundamental concepts such as magnetic fields, Lorentz force, electromagnetic induction, and their intricate interconnections. Mastery of these principles transcends mere theory, holding profound practical significance across various technological domains. This chapter unravels the intricacies of moving charges, magnetic fields’ behavior, induction phenomena, forming the cornerstone of numerous technological advancements. Through engaging with important questions moving charges and magnetism, the goal is to gain a comprehensive understanding of this pivotal chapter.

What are Moving Charges and Magnetism?

Moving Charges and Magnetism is a branch of physics that explores the relationship between electrical currents (moving charges) and magnetic fields. It investigates how the motion of charged particles, such as electrons, generates magnetic fields and how these magnetic fields, in turn, exert forces on other moving charges. This field of study encompasses concepts like the Lorentz force, magnetic fields due to current-carrying conductors, magnetic induction, and the interaction between electric and magnetic fields. Understanding this relationship is crucial in various technological applications, from motors and generators to the functioning of everyday electronic devices.oswal.io provides important questions from moving charges and magnetism class 12 which can help you in preparing for examination.

Class 12 Physics Moving Charges and Magnetism Important Questions and Answers

Q1. A rectangular, a square, a circular and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with a constant velocity
\bar{v}=v\hat{i}. The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for:
Options
(a) any of the four loops
(b) the circular and elliptical loops
(c) only the elliptical loops
(d) the rectangular, circular and elliptical loops

Ans. (b) the circular and elliptical loops

Explanation:
Consider a rectangular, a square, a circular, and an elliptical loop moving perpendicularly out from a magnetic field B with constant velocity

important questions moving charges and magnetism

From the given figure:

  • Assume that the shaded region is the area that moves out of the magnetic field in a time interval of Δt.
  • For the rectangular and square loop, the area moving out in Δt is constant, and therefore the rate of change of flux is constant. (∵ Φ = B × area)
  • For the circular and elliptical loop, the area moving out in Δt is not constant, and therefore the rate of change of flux is not constant.
  • It is known that ε = −\dfrac{dΦ}{dt}​ ⇒ induced emf ∝ rate of change of magnetic flux.
  • Hence, the emf induced will be constant in the rectangular and square loop, and emf will not remain constant for circular and elliptical loops.
Q2. If a ferromagnetic material is inserted in a current carrying solenoid, the magnetic field of solenoid:
Options
(a) largely increases
(b) slightly increases
(c) largely decreases
(d) slightly decreases

Ans. (a) largely increases
Explanation: The magnetic field inside the solenoid increases due to the high permeability of the ferromagnetic material.

Q3. A circular brass loop of radius ‘a’ and resistance R is placed with its plane perpendicular to a magnetic field which varies with time as B = B_0 sin wt. Obtain the expression for the induced current in the loop.

Explanation:
(i) Here \text{A = πa}^2 , θ = 0°. So flux linked with the loop is
Induced current,
\\ I =\dfrac{\text { Inducede. } m . f .}{\text { resis } \tan c e}=\dfrac{e}{R} \\[4.5 bp] =-\dfrac{d \phi / d t}{R}=\dfrac{-1}{R} \dfrac{d}{d t}\left(B A \cos 0^{\circ}\right) \\[4.5 bp] I =-\dfrac{A}{R} \dfrac{d}{d t}\left(B_{0} \sin \omega t\right)=-\dfrac{A B_{0}}{R} \cos \omega t(\omega) \\[4.5 bp] I =\dfrac{\pi a^{2} B_{0} \omega \cos \omega t}{R}

Q4. State Maxwell’s cork screw rule or right hand screw rule?

Explanation:
If the forward motion of a right handed imaginary conductive screw is in the direction of the current through a linear conductor, then the direction of rotation of the screw gives the direction of the magnetic lines of force around the conductor.

Screw
Q5. What is the Oersted’s experiment ?

Explanation:
When current was allowed to flow in a wire placed parallel to the axis of a magnetic needle kept directly below the wire, the needle was found to deflect from its normal position.
When current was reversed through the wire, the needle was found to deflect in the opposite direction to the earlier case.

CBSE Class 12 Physics Chapter wise Important Questions

Chapter No.Chapter Name
Chapter 1Electric Charges and Fields
Chapter 2Electrostatic Potential and Capacitance
Chapter 3Current Electricity
Chapter 4Moving Charges and Magnetism
Chapter 5Magnetism and Matter
Chapter 6Electromagnetic Induction
Chapter 7Alternating current
Chapter 8Electromagnetic Waves
Chapter 9Ray Optics and Optical Instruments
Chapter 10Wave Optics
Chapter 11Dual Nature of Radiation and Matter
Chapter 12Atoms
Chapter 13Nuclei
Chapter 14Semiconductor Electronics: Materials, Devices and Simple Circuits

Conclusion

Understanding the core principles governing the interaction of charged particles in their surroundings is fundamental to comprehending Moving Charges and Magnetism in Class 12 Physics. Platforms like oswal.io provide important questions in moving charges and magnetism facilitating comprehensive learning and preparation. These resources aid students in mastering the crucial aspects of electromagnetic science, enhancing their grasp of this integral facet of physics.

Frequently Asked Questions

Ans: When an electric current flows through a conductor, it creates a circular magnetic field around the wire. The direction of the magnetic field follows the right-hand thumb rule, determined by the direction of current flow.
Ans: Electromagnetic induction is the process where a changing magnetic field induces an electromotive force (EMF) or voltage in a nearby conductor. This phenomenon is the basis for generating electricity in generators and transformers.
Ans: Magnetic fields are regions where magnetic forces act. Charged particles moving through magnetic fields experience a force perpendicular to both their velocity and the magnetic field, causing them to follow curved paths.
Ans: Electric fields are produced by stationary charges, while magnetic fields arise from moving charges. They are interconnected through Maxwell’s equations and can influence each other, creating electromagnetic waves.
Ans: Understanding Moving Charges and Magnetism is crucial in various technological applications, including electric motors, generators, transformers, MRI machines, and the functioning of devices like speakers and hard drives.
Chapter Wise  Important Questions for CBSE Board Class 12 Physics
Electric Charges and Fields
Electrostatic Potential and Capacitance
Current Electricity
Moving Charges and Magnetism
Magnetism and Matter
Electromagnetic Induction
Alternating current
Electromagnetic Waves
Ray Optics and Optical Instruments
Wave Optics
Dual Nature of Radiation and Matter
Atoms
Nuclei
Semiconductor Electronics: Materials, Devices and Simple Circuits
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