Grade 11
  1. Mechanics  1.1. dynamics  1.1.1. Motion in one dimension  1.1.2. Motion in two and three dimensions  1.1.3. Displacement and Distance  1.1.4. Speed and Velocity  1.1.5. Acceleration and deceleration  1.1.6. Graphical analysis of motion  1.1.7. Equations of motion (advanced derivations)  1.1.8. Free fall and terminal velocity  1.1.9. Projectile motion  1.1.10. Relative velocity in one and two dimensions  1.1.11. Motion of a car on an inclined plane  1.2. Dynamics  1.2.1. Newton's laws of motion and their applications  1.2.2. Inertia and Newton's first law  1.2.3. Force and types of force  1.2.4. Static and kinetic friction  1.2.5. Circular motion and centripetal acceleration  1.2.6. Non-uniform circular motion  1.2.7. Banking of roads and curves  1.2.8. Momentum and Impulse  1.2.9. Conservation of momentum in one and two dimensions  1.2.10. Applications of Newton's Third Law  1.3. Work, Energy and Power  1.3.1. Work done by a constant and variable force  1.3.2. Work–energy theorem  1.3.3. Kinetic and potential energy  1.3.4. Gravitational and elastic potential energy  1.3.5. Conservation of mechanical energy  1.3.6. Power and instantaneous power  1.3.7. Efficiency of machines  1.3.8. Work done by conservative and non-conservative forces  1.4. Rotational motion  1.4.1. Torque and angular acceleration  1.4.2. Rotational equilibrium  1.4.3. Moment of inertia and its applications  1.4.4. Angular momentum and its conservation  1.4.5. Kinetic energy of rolling motion and rotation  1.4.6. Parallel and Perpendicular Axis Theorem  1.4.7. Dynamics of rotational motion
  2. Gravitational force  2.1. Universal gravitation  2.1.1. Newton's law of universal gravitation  2.1.2. Gravitational field and potential  2.1.3. Change in acceleration due to gravity  2.1.4. Kepler's laws of planetary motion  2.1.5. Orbital mechanics and satellites  2.1.6. Escape velocity and orbital velocity  2.1.7. Weightlessness and free fall  2.1.8. Gravitational potential energy and energy in orbits  2.1.9. Black holes and gravitational lensing
  3. Properties of matter  3.1. Fluid mechanics  3.1.1. Density and pressure in liquids  3.1.2. Pascal's theory and applications  3.1.3. Archimedes' Principle and Buoyancy  3.1.4. Bernoulli's equation and applications  3.1.5. Continuity equation and the Venturi effect  3.1.6. Surface tension and capillarity  3.1.7. Viscosity and Poiseuille's Law  3.1.8. Reynolds number and turbulence  3.2. Elasticity and deformation  3.2.1. Hooke's law and the stress-strain relation  3.2.2. Elastic modulus and applications  3.2.3. Deformation and yield strength of solids
  4. Thermal physics  4.1. Heat and temperature  4.1.1. Thermometric properties and temperature scale  4.1.2. Thermal expansion of solids, liquids and gases  4.1.3. Heat transfer system  4.1.4. Specific heat capacity and calorimetry  4.1.5. Latent heat and phase change  4.2. Kinetic theory of gases  4.2.1. Molecular model of gases  4.2.2. Kinetic explanation of temperature  4.2.3. Ideal Gas Equation and Deviations  4.2.4. Mean free path and Maxwell–Boltzmann distribution  4.3. Laws of Thermodynamics  4.3.1. Zeroth Law and Thermal Equilibrium  4.3.2. First Law and Internal Energy  4.3.3. The Second Law and Entropy  4.3.4. Carnot cycle and heat engines  4.3.5. Refrigerators and heat pumps
  5. Waves and oscillations  5.1. Simple Harmonic Motion  5.1.1. Equations of SHM  5.1.2. Energy in SHM  5.1.3. Damped and forced oscillations  5.1.4. Resonance and applications  5.1.5. Pendulum and spring-mass system  5.2. Wave motion  5.2.1. Types of mechanical waves  5.2.2. Wave motion and energy transport  5.2.3. Superposition Principle and Standing Waves  5.2.4. Reflection, Refraction and Diffraction  5.2.5. Doppler effect in sound and light  5.2.6. Pulsations and interference
  6. Electricity and Magnetism  6.1. Electrostatics  6.1.1. Electric charge and conservation  6.1.2. Coulomb's law and its applications  6.1.3. Electric field and electric flux  6.1.4. Electric potential and potential energy  6.1.5. Capacitance and Energy Stored in a Capacitor  6.2. Current Electricity  6.2.1. Ohm's law and electrical resistance  6.2.2. Resistivity and temperature dependence  6.2.3. Kirchhoff's Laws and Circuit Analysis  6.2.4. Electrical power and efficiency  6.2.5. Combination of resistors  6.3. Magnetism and Electromagnetism  6.3.1. Magnetic fields and their sources  6.3.2. Magnetic force on moving charges  6.3.3. Electromagnetic induction  6.3.4. Faraday's and Lenz's laws  6.3.5. Inductance and Transformer  6.3.6. Alternating current and its applications
  7. Optics  7.1. Reflection and Refraction  7.1.1. laws of reflection and refraction  7.1.2. Mirrors and lenses  7.1.3. Total internal reflection and optical fiber  7.2. Wave optics  7.2.1. Interference and Diffraction  7.2.2. Young's double-slit experiment  7.2.3. Polarization of light
  8. Modern Physics  8.1.1. Photoelectric effect and Einstein's theory  8.1.2. Wave–particle duality  8.1.3. Heisenberg's uncertainty principle  8.1.4. Compton Effect  8.2. Atomic and Nuclear Physics  8.2.1. Atomic model and energy levels  8.2.2. Radioactive decay and half-life  8.2.3. Nuclear Fission and Fusion
  9. Electronics and Communication  9.1. Semiconductors  9.1.1. pn junction and diode  9.1.2. Transistors and Logic Gates  9.1.3. Integrated Circuits and Applications  9.2. Communication Systems  9.2.1. Basics of Analog and Digital Communication  9.2.2. Wireless and Optical Communication  9.2.3. Modulation and Demodulation

Grade 11 → Electricity and Magnetism → Magnetism and Electromagnetism ↓


Electromagnetic induction


Electromagnetic induction is a fundamental concept in physics in which an electromotive force (EMF) is generated when a conductor is exposed to a changing magnetic field. This phenomenon forms the basis of many electrical devices and technologies, including transformers, inductors, and many types of electrical generators and motors.

Basic principles

The principle of electromagnetic induction was first discovered by Michael Faraday in 1831. According to Faraday's law of induction, the electromagnetic force induced in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the circuit.

This relation can be expressed by the following formula:

EMF = -dΦ/dt

where EMF is the electromotive force measured in volts, and Φ (phi) is the magnetic flux in webers.

Magnetic flux

Magnetic flux, represented by the Greek letter (Phi), is a measure of the amount of magnetization taking into account the strength and extent of the magnetic field. It can be calculated using the formula:

Φ = B * A * cos(θ)

Where:

  • B is the magnetic field strength in Tesla (T).
  • A is the area in square metres (m2 ).
  • θ is the angle between the magnetic field lines and the normal (perpendicular) to A

Faraday's experiments and discoveries

In one of Faraday's most famous experiments, he wrapped two coils of wire on opposite sides of an iron ring. He let a current pass through one coil and observed that when the current in the first coil was turned on or off, a current was induced in the second coil. This happens because the magnetic field produced by the first coil was changing, causing an EMF to be induced in the second coil.

Example of simple induction experiment

To explain electromagnetic induction, consider the following simple physical setup:

  1. A coil of wire, known as a solenoid, is connected to the galvanometer.
  2. A bar magnet.

When the north end of the magnet is pushed into the coil, an electric current is observed in the galvanometer. This current exists only when the magnet is in motion. Similarly, if the magnet is pulled out of the coil, the direction of the current reverses, indicating that the electromotive force was induced by the changing magnetic field.

N S

From this simple setup, let's look at the key points:

  • If there is relative motion between a magnet and a coil then EMF is induced in the circuit.
  • The strength of the induced e.m.f. is determined by the rate of change of magnetic flux.

Lenz's law

Lenz's law is a principle that further describes the behavior of induced currents. It states that the direction of the induced current is such that it opposes the change in magnetic flux that produced it. In simple terms, any induced current will create a magnetic field that opposes the motion or change that induced the current.

This can be understood mathematically by the negative sign in Faraday's law:

EMF = -dΦ/dt

Practical applications

Electromagnetic induction is used in many real-world devices and systems. Here are some key examples:

Electric generator

An electric generator converts mechanical energy into electrical energy using electromagnetic induction. When a coil rotates in a magnetic field, the magnetic flux linked with the coil changes, producing EMF and thus current.

Parent

Transformers

Transformers are devices used in electrical circuits to transfer energy between two or more coils through electromagnetic induction. They play a vital role in changing the voltage of AC currents in power systems. The principle of operation depends entirely on the induction between the coils.

Inductive charging

Wirelessly charging devices such as smartphones and electric toothbrushes uses electromagnetic induction by creating a magnetic field between the charging station and the device, allowing energy transfer to take place.

Its working mechanism is similar to that of a transformer, where the alternating current flowing in the charging base induces an alternating magnetic field, which in turn induces current in the coil inside the device.

Induction cooktops

Induction cooktops use magnetic fields to directly heat pots and pans. The cooktop itself remains cool, and the heat is concentrated in the cookware. This process occurs through electromagnetic induction, where a changing magnetic field in the cooktop induces an electric current in the metal pan, creating heat through electrical resistance.

Conclusion

Electromagnetic induction is a powerful concept that has wide applications in modern technology. Understanding its basic principles and understanding how it gives rise to induced currents and EMF gives us an idea of how many devices in our daily lives work.

From power generation to wireless charging and beyond, the principles of electromagnetic induction continue to be a cornerstone of innovation and advancement in technology.


Grade 11 → 6.3.3


U
username
0%
completed in Grade 11

← Prev (6.3.2)
Magnetic force on moving charges
Next (6.3.4) →
Faraday's and Lenz's laws

Comments 



Electromagnetic induction

https://www.physicsflow.com/g11/6.3.3?pfal=en