Class 12 Physics Chapter 4 Moving Charges and Magnetism – Revision Notes

Quick revision notes for Class 12 Physics Chapter 4 (Moving Charges and Magnetism). These Class 12 Physics Chapter 4 notes are ideal for quick revision just before exams.

Forces

• Lorentz force: F=qv×B; on wire: F=IL×B.
• Circular motion: r=mv/(qB); T=2πm/(qB).
• Velocity selector: v=E/B.

Fields & Laws

• Biot-Savart: dB=(μ₀/4π)(I dl×r̂)/r².
• Straight wire: B=μ₀I/2πr; solenoid: B=μ₀nI.
• Ampere’s law: ∮B·dl=μ₀I_enc.
• Parallel currents: F/l=μ₀I₁I₂/2πd.

One-Line Summary

Moving charges experience magnetic (Lorentz) forces causing circular motion, while currents generate magnetic fields per Biot-Savart and Ampere’s laws, enabling galvanometer-based current/voltage measurement.

Written by Satish

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