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 ↓


Alternating current and its applications


Alternating current (AC) is an essential concept in electricity and magnetism and plays a vital role in our daily lives. It is the type of electric current that is typically used for residential and commercial power supplies. To understand the applications of AC, it is important to understand how AC works and how it fits into the broader concepts of magnetism and electromagnetism.

Basic understanding of alternating current (AC)

Alternating current means the flow of electric charge changes direction periodically, while in direct current (DC) the direction of flow remains constant. In AC the flow changes direction at regular intervals, which provides distinct advantages in power transmission over long distances.

Production of AC voltage

AC voltage is usually produced using generators where mechanical energy is converted into electrical energy. An important part of this process involves electromagnetic induction, a phenomenon where a changing magnetic field induces an electromotive force (emf) in a conductor.

EMF = -N (dΦ/dt)

Here:

  • N is the number of turns in the coil.
  • dΦ /dt is the rate of change of magnetic flux.

As the generator spins, the magnetic field lines intersect the coil at different angles, producing a sinusoidal AC wave.

AC power and frequency

AC power is described by its frequency and amplitude. Frequency is the number of cycles completed by the current per second, measured in hertz (Hz). In many countries a standard frequency for domestic AC power is 50 Hz or 60 Hz.

The amplitude or maximum voltage of AC is the maximum value of current. However, in AC circuits it is necessary to consider the Root Mean Square (RMS) value which is given as follows:

V rms = V peak / √2

Transmission of electricity

A significant advantage of using AC over DC is its ability to transmit power effectively over long distances. This efficiency is achieved by changing the voltage levels using transformers. Transformers work on the principle of electromagnetic induction and can increase (step-up) or decrease (step-down) the voltage levels.

primary Secondary

Transformers

Transformers play a vital role in efficient power distribution by increasing voltage levels for transmission and reducing voltage levels for local distribution. The formula governing transformer operation is:

V p /V s = N p /N s

Where:
V p and V s are the primary and secondary voltages,
N p and N s are the number of turns in the primary and secondary coils.

Applications of AC

1. Household electricity

AC is used for all residential and commercial power needs because it is easy to convert and distribute. AC appliances include lights, refrigerators, air conditioners, and many other types of appliances.

2. Industrial applications

AC powers countless industrial machines and motors. Electric motors that run on AC are an integral part of manufacturing and production processes.

3. Electricity generation and distribution

Most power plants generate electricity in the form of AC. It is then transmitted through power lines and distributed to homes and industries. The efficient transmission of AC over long distances makes it the backbone of the modern electric grid.

Understanding AC Circuit Components

Resistors in AC Circuits

In AC circuits, resistors obstruct the flow of current just like in DC circuits. However, the alternating nature of the current makes the calculations a little different.

I = V rms / R

Capacitors and Inductors in AC Circuits

Capacitors and inductors introduce reactance into AC circuits, a concept that represents resistance to a change in current flow due to capacitive or inductive properties.

The reactance ( X C ) of a capacitor is given by:

X C = 1 / (2πfC)

The reactance ( X L ) of an inductor is:

X L = 2πfL

Where f is the frequency, C is the capacitance, and L is the inductance.

Conclusion

Alternating current is a fundamental part of electrical systems. Its ability to transmit efficiently over long distances and easily adapt voltage levels makes it indispensable in our daily lives. Understanding the principles of AC in physics provides insight into the operation and applications of a wide range of devices and systems that shape modern society.


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Alternating current and its applications

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