Topics
Electric Charges and Fields
- Electric Charge
- Electrical Conduction in Solids
- Electric Field
- Electric Field Due to a System of Charges
- Physical Significance of Electric Field
- Electric Lines of Force
- Electric Flux
- Electric Dipole
- Dipole in a Uniform External Field
- Continuous Charge Distribution
- Gauss’s Law
- Charging by Induction
- Uniformly Charged Infinite Plane Sheet and Uniformly Charged Thin Spherical Shell (Field Inside and Outside)
- Overview: Gauss' Theorem
- Conductors and Insulators
- Electric Field due to an Electric Dipole
Electrostatics
Electrostatic Potential and Capacitance
- Electric Potential
- Potential Due to a Point Charge
- Potential Due to an Electric Dipole
- Equipotential Surfaces
- Relation Between Electric Field and Electrostatic Potential
- Potential Energy of a System of Charges
- Potential Energy of a Single Charge
- Potential Energy of a System of Two Charges in an External Field
- Potential Energy of a Dipole in an External Field
- Electrostatics of Conductors
- Capacitors and Capacitance
- The Parallel Plate Capacitor
- Effect of Dielectric on Capacity
- Combination of Capacitors
- Energy Stored in a Charged Capacitor
- Van De Graaff Generator
- Capacitance of a Parallel Plate Capacitor with and Without Dielectric Medium Between the Plates
- Conductors and Insulators Related to Electric Field
- Electric Potential
- Overview: Electric Potential
- Overview: Capacitors and Dielectrics
Current Electricity
Current Electricity
- Electric Current
- Electric Current and Its Related Concepts
- Ohm's Law
- Drift of Electrons and the Origin of Resistivity
- Limitations of Ohm’s Law
- Resistivity of Various Materials
- Temperature Dependence of Resistance
- Electrical Power
- Cells, Emf, Internal Resistance
- Cells in Series
- Kirchhoff’s Laws
- Wheatstone Bridge
- Conductivity and Conductance
- Delta Star Transformation
- Potential Difference and Emf of a Cell
- Measurement of Internal Resistance of a Cell
- Resistors in Parallel
- Specific Resistance or Electrical Resistivity
- V-I Characteristics (Linear and Non-linear)
- Flow of Electric Charges in a Metallic Conductor
- Overview: Electric Resistance and Ohm's Law
- Overview: DC Circuits and Measurements
Magnetic Effects of Current and Magnetism
Electromagnetic Induction and Alternating Currents
Moving Charges and Magnetism
- Magnetic force
- Sources and Fields of Magnetic Force
- Magnetic Field, Lorentz Force
- Force on a Current Carrying Conductor in a Magnetic Field
- Motion in a Magnetic Field
- Biot-Savart Law
- Applications of Biot-Savart's Law > Magnetic Field on the Axis of a Circular Current-Carrying Loop
- Ampere’s Circuital Law
- Solenoid and the Toroid - the Solenoid
- Force Between Two Parallel Currents, the Ampere
- Circular Current Loop as a Magnetic Dipole
- Torque on a Rectangular Current Loop in a Uniform Magnetic Field
- Moving Coil Galvanometer
- Oersted's Experiment
- Solenoid and the Toroid - the Toroid
- Magnetic Diapole
- Torque on a Current-Loop in a Uniform Magnetic Field
- Force on a Current Carrying Conductor in a Magnetic Field
- Force on a Moving Charge in Uniform Magnetic and Electric Fields
- Straight and Toroidal Solenoids (Only Qualitative Treatment)
- The Magnetic Dipole Moment of a Revolving Electron
- Velocity Selector
- Cyclotron
- Overview: Moving Charges and Magnetic Field
- Overview: Torque on a Current-Loop : Moving-Coil Galvanometer
Electromagnetic Waves
Magnetism and Matter
- Concept of Magnetism
- Bar Magnet and Solenoid Analogy
- Magnetism and Gauss’s Law
- Magnetisation and Magnetic Intensity
- Magnetic Properties of Materials
- Permanent Magnet
- Curie Law of Magnetism
- Hysteresis: Retentivity and Coercivity
- The Earth’s Magnetism
- Torque on a Magnetic Dipole (Bar Magnet) in a Uniform Magnetic Field
- Dipole in a Uniform External Field
- Magnetic Field Due to Magnetic Dipole (Bar Magnet)
- Magnetic Field due to a Bar Magnet
- Magnetic Dipole Moment of a Revolving Electron
- Current Loop as a Magnetic Dipole
- Magnetic Substances
- Overview: Magnetism and Mater
Electromagnetic Induction
- Electromagnetic Induction
- The Experiments of Faraday and Henry
- Magnetic Flux
- Faraday's Laws of Electromagnetic Induction
- Lenz’s Law and Conservation of Energy
- Motional Electromotive Force (e.m.f.)
- Mutual Inductance
- Self Inductance
- A.C. Generator
- Energy Consideration: a Quantitative Study
- Eddy Currents or Foucault Currents
- Induced Current and Induced Charge
- Overview - Electromagnetic Induction
Optics
Dual Nature of Radiation and Matter
Alternating Current
- Alternating current (AC) and Direct Current (DC)
- Different Types of AC Circuits: AC Voltage Applied to a Resistor
- Representation of AC Current and Voltage by Rotating Vectors - Phasors
- Different Types of AC Circuits: AC Voltage Applied to an Inductor
- Different Types of AC Circuits: AC Voltage Applied to a Capacitor
- Different Types of AC Circuits: AC Voltage Applied to a Series LCR Circuit
- Power in AC Circuit
- Forced Oscillations and Resonance
- Transformers
- LC Oscillations
- Reactance and Impedance
- Peak and Rms Value of Alternating Current Or Voltage
- Overview: AC Circuits
Electromagnetic Waves
- Elementary Facts About Electromagnetic Wave Uses
- Electromagnetic Spectrum
- Transverse Nature of Electromagnetic Waves
- EM Wave
- Displacement Current
- Overview of Electromagnetic Waves
Atoms and Nuclei
Ray Optics and Optical Instruments
- Reflection of Light by Spherical Mirrors
- Refraction of Light
- Refraction at a Spherical Surface and Lenses
- Refraction by a Lens
- Refraction at Spherical Surfaces
- Power of a Lens
- Refraction of Light Through a Prism
- Optical Instruments
- Simple Microscope or a Reading Glass
- Compound Microscope
- Telescope
- Optical Instruments: the Eye
- Laws of Refraction
- Spherical Mirror > Concave Mirror
- Rarer and Denser Medium
- Lens Maker's Formula
- Thin Lens Formula
- Concept of Lenses
- Some Natural Phenomena Due to Sunlight
- Dispersion by a Prism
- Magnification
- Total Internal Reflection
- Ray Optics - Mirror Formula
- Overview of Ray Optics and Optical Instruments
- Light Process and Photometry
Electronic Devices
Communication Systems
Wave Optics
- Introduction of Wave Optics
- Huygens' Principle
- Refraction of a Plane Wave
- Refraction at a Rarer Medium
- Reflection of a Plane Wave by a Plane Surface
- Coherent and Incoherent Addition of Waves
- Interference of Light Waves and Young’s Experiment
- Diffraction of Light
- The Single Slit
- Seeing the Single Slit Diffraction Pattern
- Refraction of Monochromatic Light
- Polarisation
- Law of Malus
- Principle of Superposition of Waves
- Corpuscular Theory
- Plane Polarised Light
- The Validity of Ray Optics
- Doppler Effect
- Width of Central Maximum
- Resolving Power of Microscope and Astronomical Telescope
- Interference
- Proof of Laws of Reflection and Refraction Using Huygens' Principle
- Brewster's Law
- Fraunhofer Diffraction Due to a Single Slit
- Coherent and Incoherent Sources and Sustained Interference of Light
- Speed of Light
- Reflection and Refraction of Plane Wave at a Plane Surface Using Wave Fronts
- Overview: Wave Optics
The Special Theory of Relativity
Dual Nature of Radiation and Matter
- Dual Nature of Radiation
- Electron Emission
- Photoelectric Effect - Hertz’s Observations
- Photoelectric Effect - Hallwachs’ and Lenard’s Observations
- Experimental Study of Photoelectric Effect
- Photoelectric Effect and Wave Theory of Light
- Einstein’s Photoelectric Equation: Energy Quantum of Radiation
- Particle Nature of Light: The Photon
- Einstein’s Equation - Particle Nature of Light
- Davisson and Germer Experiment
- de-Broglie Relation
- Wave Nature of Matter
- Overview: Dual Nature of Radiation and Matter
Atoms
- Introduction of Atoms
- Alpha-particle Scattering and Rutherford’s Nuclear Model of Atom
- Atomic Spectra
- Bohr’s Model for Hydrogen Atom
- Energy Levels
- The Line Spectra of the Hydrogen Atom
- De Broglie’s Explanation of Bohr’s Second Postulate of Quantisation
- Heisenberg and De Broglie Hypothesis
- Thompson Model
- Dalton's Atomic Theory
- Hydrogen Spectrum
- Overview: Atoms
Nuclei
- Composition of Nucleus
- Size of the Nucleus
- Mass - Energy
- Binding Energy per Nucleon
- Nuclear Force
- Alpha Decay
- Beta Decay
- Gamma Decay
- Controlled Thermonuclear Fusion
- Nuclear Reactor
- Mass Defect and Binding Energy
- Atomic Mass, Mass - Energy Relation and Mass Defect
- Overview: Nuclei
- Law of Radioactive Decay
Semiconductor Electronics - Materials, Devices and Simple Circuits
- Concept of Semiconductor Electronics: Materials, Devices and Simple Circuits
- Classification of Metals, Conductors and Semiconductors
- Energy Bands in Solids
- Intrinsic Semiconductor
- Extrinsic Semiconductor
- p-n Junction
- Semiconductor Diode
- Application of Junction Diode as a Rectifier
- Integrated Circuits
- Feedback Amplifier and Transistor Oscillator
- Transistor as a Device
- Basic Transistor Circuit Configurations and Transistor Characteristics
- Transistor Action
- Transistor: Structure and Action
- Digital Electronics and Logic Gates
- Transistor as an Amplifier (Ce-configuration)
- Transistor and Characteristics of a Transistor
- Zener Diode as a Voltage Regulator
- Special Purpose P-n Junction Diodes
- Diode as a Rectifier
- Triode
- Overview: Semiconductor Electronics
Communication Systems
- Detection of Amplitude Modulated Wave
- Production of Amplitude Modulated Wave
- Basic Terminology Used in Electronic Communication Systems
- Sinusoidal Waves
- Modulation and Its Necessity
- Amplitude Modulation (AM)
- Need for Modulation and Demodulation
- Satellite Communication
- Propagation of EM Waves
- Bandwidth of Transmission Medium
- Bandwidth of Signals
The Special Theory of Relativity
- The Special Theory of Relativity
- The Principle of Relativity
- Maxwell'S Laws
- Kinematical Consequences
- Dynamics at Large Velocity
- Energy and Momentum
- The Ultimate Speed
- Twin Paradox
Estimated time: 4 minutes
CBSE: Class 12
Key Points: Einstein's Photoelectric Equation: Energy Quantum of Radiation
- Einstein proposed that light consists of quanta (photons), each with energy E = hν.
- When a photon of energy hν falls on a metal, it is completely absorbed by one electron.
- The electron uses energy Φ (work function) to escape, and the rest appears as kinetic energy.
Einstein's Photoelectric Equation: Kmax = hν − ϕ0
or equivalently: \[\frac{1}{2}mv_{max}^2=h\nu-h\nu_0=h(\nu-\nu_0)\]
- If ν < ν0: v2 is negative → imaginary velocity → no photoelectric emission possible.
- If ν > ν0: v2 is positive → emission occurs.
- Increasing intensity → more photons → more electrons, but same KE per electron.
- Increasing frequency → more energy per photon → higher KE of emitted electrons.
- Photoelectric emission is a 'knock-out' process: one photon knocks out one electron with KE = ½mv².
Important Note on Photocurrent vs Frequency:
- Increasing frequency does NOT increase the number of photoelectrons → photocurrent does not increase with frequency.
- Photocurrent depends only on the number of photons (i.e., intensity).
