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 📚 Chapter: Magnetism and Matter – Class 12 Physics Notes --- 🔸 1. Introduction This chapter deals with the magnetic properties of materials, Earth's magnetism, and how magnetism and matter are related. --- 🔹 2. Bar Magnet Magnetic dipole has two poles: North and South Like poles repel, unlike poles attract Magnetic field lines emerge from North and enter South Magnetic dipole moment (M): M = m × 2l where, m = pole strength, 2l = length of magnet --- 🔹 3. Magnetic Field Due to a Bar Magnet At a point on the axial line: B_{\text{axial}} = \frac{\mu_0}{4\pi} \cdot \frac{2M}{r^3} At a point on the equatorial line: B_{\text{equatorial}} = \frac{\mu_0}{4\pi} \cdot \frac{M}{r^3} --- 🔹 4. Torque on a Magnetic Dipole in Uniform Magnetic Field \vec{\tau} = \vec{M} \times \vec{B} Where: M = Magnetic dipole moment B = External magnetic field Direction by right-hand rule --- 🔹 5. Magnetic Properties of Materials Type Magnetic Susceptibility (χ) Relative Permeability (μr) Example Diamagne...

 Chapter: Magnetism and Matter – Class 12 Physics Notes 🔸 Introduction: Magnetism is the phenomenon associated with the motion of electric charges, which gives rise to magnetic fields. This chapter explores bar magnets, Earth's magnetism, magnetic materials, and related laws. --- 🔹 1. The Bar Magnet A bar magnet has two poles: North (N) and South (S). Magnetic field lines emerge from the North pole and enter the South pole. Magnetic field strength is strongest at the poles. Magnetic Moment (M): \vec{M} = m \times 2l  = magnetic pole strength  = length of the magnet Torque on a Bar Magnet in Magnetic Field: \vec{\tau} = \vec{M} \times \vec{B} Potential Energy: U = -\vec{M} \cdot \vec{B} --- 🔹 2. Earth’s Magnetism Earth behaves like a giant bar magnet. The magnetic field of Earth is called geomagnetic field. Important terms: Magnetic Declination (D): Angle between geographic meridian and magnetic meridian. Magnetic Inclination or Dip (I): Angle between Earth's magnetic f...