Topics
Electric Charges and Fields
- Electric Charge
- Conductors and Insulators
- Basic Properties of Electric Charge
- Coulomb’s Law
- Forces between Multiple Charges
- Electric Field
- Electric Field Due to a System of Charges
- Physical Significance of Electric Field
- Electric Field Lines
- Electric Flux
- Electric Dipole
- Dipole in a Uniform External Field
- Continuous Charge Distribution
- Gauss’s Law
- Application of Gauss' Law
Electrostatics
Electrostatic Potential and Capacitance
- Electric Potential and Potential Energy
- Electrostatic Potential
- Electric Potential Due to a Point Charge
- Potential Due to an Electric Dipole
- Potential due to a System of Charges
- 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
- Dielectrics and Polarisation
- Capacitors and Capacitance
- The Parallel Plate Capacitor
- Effect of Dielectric on Capacitance
- Combination of Capacitors
- Energy Stored in a Charged Capacitor
Current Electricity
Current Electricity
- Electric Current
- Electric Currents in Conductors
- Ohm's Law
- Drift of Electrons and the Origin of Resistivity
- Mobility of Electrons
- Limitations of Ohm’s Law
- Resistivity of Various Materials
- Temperature Dependence of Resistivity
- Electrical Energy and Power in Conductors
- Cells, EMF, and Internal Resistance
- Cells in Series and in Parallel
- Kirchhoff’s Laws
- Wheatstone Bridge
Magnetic Effects of Current and Magnetism
Moving Charges and Magnetism
- Electromagnetism
- Magnetic force
- Motion in a Magnetic Field
- Biot-Savart Law
- Magnetic Field on the Axis of a Circular Current-Carrying Loop
- Ampere’s Circuital Law
- Solenoid
- Force Between Two Parallel Currents (Ampere’s Law)
- Torque on a Rectangular Current Loop in a Uniform Magnetic Field
- Circular Current Loop as a Magnetic Dipole
- Moving Coil Galvanometer
- Overview: Moving Charges and Magnetic Field
- Overview: Torque on a Current-Loop : Moving-Coil Galvanometer
Electromagnetic Induction and Alternating Currents
Magnetism and Matter
- Concept of Magnetism
- The Bar Magnet
- Magnetic Field Lines
- Bar Magnet as an Equivalent Solenoid
- The Dipole in a Uniform Magnetic Field
- The Electrostatic Analog
- Magnetism and Gauss’s Law
- Magnetisation and Magnetic Intensity
- Magnetic Properties of Materials
- Overview: Magnetism and Mater
Electromagnetic Waves
Optics
Electromagnetic Induction
Dual Nature of Radiation and Matter
Alternating Current
- AC Voltage Applied to a Resistor
- Representation of AC Current and Voltage by Rotating Vectors - Phasors
- AC Voltage Applied to an Inductor
- AC Voltage Applied to a Capacitor
- AC Voltage Applied to a Series LCR Circuit
- Phasor-diagram Solution
- Resonance
- Power in AC Circuit
- Transformers
- Overview: AC Circuits
Atoms and Nuclei
Electromagnetic Waves
- Concept of Electromagnetic Waves
- Displacement Current
- Sources of Electromagnetic Waves
- Nature of Electromagnetic Waves
- Electromagnetic Spectrum
- Overview of Electromagnetic Waves
Electronic Devices
Ray Optics and Optical Instruments
- Ray Optics Or Geometrical Optics
- Reflection of Light by Spherical Mirrors
- Sign Convention for Reflection by Spherical Mirrors
- Focal Length of Spherical Mirrors
- Mirror Equation of Spherical Mirrors
- Refraction of Light
- Total Internal Reflection
- Applications of Total Internal Reflection
- Refraction at a Spherical Surfaces
- Refraction by a Lens
- Power of a Lens
- Combined Focal Length of Two Thin Lenses in Contact
- Refraction of Light Through a Prism
- Optical Instruments
- Microscope and it’s types
- Telescope
- Overview of Ray Optics and Optical Instruments
Communication Systems
Wave Optics
- Concept 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
- Polarisation of Light
- 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
- Effects of Intensity and Frequency on Photocurrent
- Photoelectric Effect and Wave Theory of Light
- Einstein’s Photoelectric Equation: Energy Quantum of Radiation
- Particle Nature of Light: The Photon
- Wave Nature of Matter
- Overview: Dual Nature of Radiation and Matter
Atoms
Nuclei
- Atomic Masses and Composition of Nucleus
- Size of the Nucleus
- Mass - Energy
- Nuclear Binding Energy
- Nuclear Force
- Radioactivity
- Forms of Energy > Nuclear Energy
- Nuclear Fission
- Nuclear Fusion
- Controlled Thermonuclear Fusion
- Overview: Nuclei
Semiconductor Electronics - Materials, Devices and Simple Circuits
- Concept of Semiconductor Electronics
- Classification of Metals, Conductors and Semiconductors
- Intrinsic Semiconductor
- Extrinsic Semiconductor
- n-type Semiconductor
- p-type Semiconductor
- Diode or p-n Junction
- Semiconductor Diode
- Application of Junction Diode as a Rectifier
- 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: 6 minutes
CBSE: Class 12
Introduction
For a long time, electricity and magnetism were studied as separate phenomena. A major breakthrough came in 1820, when Hans Christian Oersted observed that an electric current affects a nearby compass needle, showing that electricity and magnetism are related.
- A stationary electric charge produces only an electric field.
- A moving electric charge produces a magnetic effect in addition to the electric effect.
- Therefore, electric current produces a magnetic field around a conductor.
CBSE: Class 12
Definition: Electromagnetism
Electromagnetism is the branch of physics that studies the relationship between electric charges, electric current, and magnetic effects.
CBSE: Class 12
Oersted's Experiment
Oersted's experiment demonstrated that a current-carrying conductor produces a magnetic field around it.
Aim
To show that electricity and magnetism are linked through electric current.
Apparatus
- Straight conducting wire
- Battery or current source
- Key/switch
- Compass needle
- Iron filings (for field pattern demonstration)
Procedure
- Place a compass needle near a straight conducting wire.
- Pass an electric current through the wire.
- Observe the change in the direction of the compass needle.
- Change the current or vary the distance between the wire and the compass.
- Sprinkle iron filings around the conductor to study the field pattern.
Observations
- The compass needle gets deflected when current flows through the wire.
- The deflection is tangential to imaginary circles around the wire.
- A greater current produces a greater deflection.
- Increasing the distance from the wire reduces the effect on the compass needle.
- Iron filings arrange themselves in concentric circles around the conductor.
Conclusion
A current-carrying conductor produces a magnetic field around it. This proved that moving charges are responsible for magnetic effects.
CBSE: Class 12
Magnetic Field Around a Straight Current-Carrying Wire
The magnetic field lines around a long, straight, current-carrying wire are circular and centred on the wire. These circles lie in planes perpendicular to the wire.
Key characteristics
- Magnetic field lines form concentric circles around the conductor.
- The magnetic field becomes stronger when the current increases.
- The magnetic field becomes weaker as the distance from the wire increases.
- The direction of the field depends on the direction of the current.
