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- Magnetism : A force caused by moving electric charges. It can attract or repel materials like iron, cobalt, and nickel.
- Magnetic Field : A region around a magnetic material or current-carrying wire where magnetic forces can be observed.
- Magnetic Field Lines : Imaginary lines that show the direction of the magnetic field.
- They flow from north to south outside the magnet.
- Magnetic Dipole : A magnetic system with two poles – north and south – like a bar magnet or a current loop.
- Gauss’s Law for Magnetism: The net magnetic flux through any closed surface is zero.
- This implies magnetic monopoles don’t exist.
- Coulomb’s Law in Magnetism: No direct Coulomb’s law like in electrostatics. However, magnetic poles interact in a similar inverse-square law fashion.
- Oersted’s Experiment: Demonstrated that electric current produces a magnetic field.
- Right-Hand Thumb Rule: Used to find the direction of the magnetic field around a current-carrying wire.
- Fleming’s Left-Hand Thumb Rule: Used to find the direction of force on a current-carrying conductor in a magnetic field.
- Lorentz Law : Describes the force on a charged particle due to electric and magnetic fields.
- Magnetic Induction (B): Magnetic field induced in a material when placed in an external magnetic field.
- Magnetic Permeability(μ): Measure of how easily a material can support the formation of a magnetic field.
- Intensity of Magnetization (I or M): Magnetic moment per unit volume of a material.
- Magnetic Force or Magnetic Intensity (H): The external magnetic field applied to a material.
- Magnetic Flux (Φ): Total magnetic field passing through a surface;
- Magnetic Susceptibility (χ): The ratio of intensity of magnetization (M) to magnetic field intensity (H);
- χ = M / H.
- Paramagnetic : Materials weakly attracted to magnetic fields (χ > 0).
- Diamagnetic : Materials repelled by magnetic fields (χ < 0).
- Ferromagnetic : Materials strongly attracted and can retain magnetization (e.g., iron).
- Curie Temperature : The temperature above which ferromagnetic materials become paramagnetic.
- Hysteresis Loss : Energy loss in magnetic materials due to the lag between magnetization and the external field.
- Inductor : A coil of wire that stores energy in a magnetic field when current flows through it.
- Inductance : (L): Property of an inductor to resist change in current;
- Choke Coil : An inductor used to block high-frequency AC while allowing DC to pass.
- Magnetic Force (on a moving charge): 𝐹 ⃗ = 𝑞 ( 𝑣 ⃗ × 𝐵 ⃗ )
- Solenoid : A long coil of wire that produces a uniform magnetic field when current passes.
- Toroid : A donut-shaped coil used to produce a confined magnetic field.
- Transformer :
- Device using mutual induction to change voltage levels in AC circuits.
- Self Induction : The process in which a changing current in a coil induces an EMF in the same coil.
- Mutual Inductance : When a change in current in one coil induces an EMF in a nearby coil.
- Electro Magnetic Induction : Generation of EMF by changing magnetic flux.
- Faraday Laws of EMI :
- An EMF is induced when magnetic flux through a circuit changes.
- The magnitude of induced EMF is proportional to the rate of change of flux.
- Lenz’s Law : The direction of induced EMF opposes the change in flux that caused it.
- Eddy Current : Loops of induced current in conductors exposed to changing magnetic fields; cause energy loss as heat.
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