Moving Charges & Magnetism: 30 Expert-Level MCQs for Class 12 Physics

Chapter 4 – Moving Charges and Magnetism (Class 12 Physics)

🔍 Chapter Overview:

“Moving Charges and Magnetism” is a crucial chapter in Class 12 Physics that explores how electric currents (moving charges) produce magnetic fields and how these fields interact with other moving charges. It lays the foundation for understanding electromagnetism, which is essential for both board exams and competitive tests like JEE and NEET.

The chapter merges theoretical concepts with mathematical formulations, making it both concept-heavy and numerically intensive.

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📚 Key Topics Covered:

1. Magnetic Force on a Moving Charge

   1. Lorentz force

   2. Motion in a uniform magnetic field

2. Magnetic Force on a Current-Carrying Conductor

   1. Force on straight wire

   2. Force between two parallel current-carrying wires (basis of ampere)

3. Torque on Current Loop

   1. Magnetic dipole moment

   2. Applications like electric motor principles

4. Biot–Savart Law

   1. Magnetic field due to a current element

   2. Application to circular loop

5. Ampere’s Circuital Law

   1. Magnetic field in solenoids and toroids

6. Solenoid and Toroid

   1. Characteristics and field patterns

   2. Ideal vs practical devices

7. Motion in Combined Electric and Magnetic Fields

   1. Velocity selector

   2. Cyclotron – Principle and working

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💡 Why This Chapter is Important:

• Forms the basis for Electromagnetic Induction and Alternating Current
• Frequent MCQs and numericals in NEET, JEE, CUET
• Key for understanding real-world applications like motors, generators, and particle accelerators

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📌 Formulae to Remember:

• Magnetic force on a charge: F = q(v × B)
• Force on a conductor: F = I(L × B)
• Magnetic field of a long straight wire: B = μ₀I / 2πr
• Field inside a solenoid: B = μ₀nI
• Torque on current loop: τ = nIBA sinθ

Moving Charges and Magnetism Quiz

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