Physics
Build intuition for motion, forces, energy, electricity, optics, and modern physics through first-principles reasoning.
01
Electric Charges and FieldsElectricity begins with a simple observation: certain materials attract each other when rubbed.
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02Electrostatic Potential and CapacitanceJust as water flows downhill from high to low potential, electric charges naturally move from high potential to low potential.
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03Current ElectricityWhen charges flow, magic happens. A river of electrons moving through a wire creates the current that powers civilization.
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04Moving Charges and MagnetismA current-carrying wire deflects a compass needle. This simple observation reveals a profound truth: electricity and magnetism are intimately connected.
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05Magnetism and MatterWhy are some materials attracted to magnets while others are repelled? The answer lies within atoms themselves.
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06Electromagnetic InductionA compass needle moves when a current flows nearby. A light bulb flickers when a transformer is switched on.
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07Alternating CurrentUnlike the constant voltage of a battery, household electricity oscillates sinusoidally—it swaps direction 50 or 60 times per second depending on your…
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08Electromagnetic WavesLight is not the only electromagnetic wave.
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09Ray Optics and Optical InstrumentsWhen light wavelengths are tiny compared to objects it encounters, we can treat light as rays traveling in straight lines until they reflect or refract.
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10Wave OpticsRay optics breaks down when light encounters obstacles smaller than its wavelength.
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11Dual Nature of Radiation and MatterLight behaves like a wave in some experiments (interference, diffraction) and like particles in others (photoelectric effect, Compton scattering).
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12AtomsAtoms are the building blocks of matter, yet they're not indivisible as ancient Greeks believed.
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13NucleiAt the heart of every atom lies the nucleus—a tiny, dense collection of protons and neutrons bound together by the strong nuclear force, the most…
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14Semiconductor Electronics: Materials, Devices and Simple CircuitsBefore the transistor (1948), electronics meant vacuum tubes—fragile, hot, and power-hungry.
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