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 ↓


Current Electricity


In our modern world, electricity is an essential component that powers our homes, offices, and countless devices. Understanding how electricity works involves exploring various concepts, one of which is "current electricity." In this explanation, we will delve deep into the details of current electricity, its nature, the principles behind it, and its applications.

What is current electricity?

Electric current is the flow of electrical charge through a conductor. It is essentially the movement of electrons in a structured path within a material. This flow of charge powers electronic devices, lights up rooms, and provides the energy needed to run countless appliances and devices.

Components of electric current

To understand current electricity it is necessary to be familiar with the following components:

  • Charge: The basic unit of electric charge is represented by the symbol q. Charge is measured in coulombs (C). An electron has a negative charge of about -1.6 × 10 -19 C
  • Current: The flow of electric charge through a conductor per unit time is called electric current. It is represented by the letter I and is measured in amperes (A). One ampere is equal to one coulomb of charge passing through a point in the circuit in one second.

The mathematical representation of electric current is:

I = q / t

Where:

  • I is the current in amperes (A)
  • q is the charge in coulomb (C)
  • t is the time in seconds (s)

Nature of electric current

Electric current may be classified into two categories:

  1. Direct current (DC): In direct current the electric charge flows in one direction only. It is commonly used in batteries, solar panels, and electronic devices. A simple cell or battery is the source of DC.
  2. Alternating current (AC): In alternating current the direction of flow of electric charge changes periodically. AC is commonly used for power transmission over long distances and in domestic power systems.

Visual example: direct vs. alternating current

DC AC

In the visual representation, the steady line represents DC where the flow of charge remains constant; the wavy red line represents AC where the direction of charge changes periodically.

Ohm's law: the basics of electrical circuits

Ohm's law is fundamental in understanding how electric current works. It relates voltage ((V)), current ((I)), and resistance ((R)) in electrical circuits. Ohm's law is expressed by the formula:

V = I * R

Where:

  • V is the voltage at the load (in volts)
  • I is the current flowing through the load (in amperes)
  • R is the resistance of the load in ohms (Ω)

This principle helps in designing circuits to ensure that devices get the right amount of power without overloading or damaging components.

Visual example: Ohm's law in a circuit

R , ,

Here is a simple circuit with a resistance (R) showing the connections to a voltage source. Current (I) flows through the circuit, causing a voltage (V) to appear across the resistor.

Resistance and conductivity

Resistance is a measure of how much a material opposes the flow of electric current. It depends on factors such as the nature of the material, length, cross-sectional area and temperature. Conductivity is the inverse of resistance and shows how easily current can flow through the material.

Major factors affecting resistance:

  • Material: Conductors like copper have low resistance, while bad conductors like rubber have high resistance.
  • Length: As the length of the conductor increases, its resistance also increases.
  • Cross-sectional area: Thicker wires have lower resistance than thinner wires.
  • Temperature: As temperature increases in conductors, resistance also increases.

Electric power

Electric power measures the rate at which electrical energy is transferred through an electric circuit. It is the product of voltage and current and is measured in watts (W). The formula for electric power (P) is:

P = V * I

This formula can also be expressed using Ohm's law:

P = I^2 * R

Or:

P = V^2 / R

Simple circuit example

Consider a simple circuit in which a battery and a resistor are connected in series. If the battery provides a voltage of 9 volts and the resistance of the resistor is 3 ohms, the current flowing through the circuit can be calculated using Ohm's law:

I = V / R
    I = 9V / 3Ω = 3A

Calculation of electrical power

The electric power consumed by the resistor can be calculated as:

P = V * I
    P = 9V * 3A = 27W

Effects of electric current

1. Heating effect

When electric current passes through a conductor, heat is generated due to the resistance of the conductor. This is the principle behind electric heaters and devices that rely on heating elements.

2. Magnetic effect

Electric current creates a magnetic field around the conductor. This principle is used in devices such as electromagnets and electric motors.

3. Chemical effect

Passing an electric current through a liquid solution causes a chemical change, called electrolysis. This is used in processes such as electroplating, which is used to deposit a thin layer of metal on objects.

Practical electricity applications

Current electricity has many uses in everyday life. Here are some practical examples:

1. Lighting

Electric lights convert electrical energy into light energy, thereby illuminating homes and streets.

2. Motors and drives

Electric motors convert electrical energy into mechanical energy, which is used in fans, mixers, and vehicles.

3. Communication

Telecommunications devices rely on electric current to transmit signals through wires or the air.

4. Heating

Electric heaters, ovens, and toasters use the heating effect of electric current to produce heat for cooking and warming.

5. Electronics

Electronic gadgets including computers and smartphones operate on the principles of electromagnetism to process and communicate information.

Conclusion

Electric current is a fundamental concept in physics and an essential aspect of modern life. Its applications are very wide, ranging from simple lighting to complex computer systems. Understanding the principles of electric current, Ohm's law, resistance and power equips us with the knowledge to use electricity effectively and safely in various technologies.


Grade 11 → 6.2


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Current Electricity

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