Grade 10
  1. Mechanics  1.1. Dynamics  1.1.1. Motion in one dimension  1.1.2. Motion in two dimensions  1.1.3. Displacement and Distance  1.1.4. Speed and Velocity  1.1.5. Acceleration  1.1.6. Graphical representation of motion  1.1.7. Equations of motion  1.1.8. Free fall and acceleration due to gravity  1.1.9. Projectile motion  1.1.10. Relative speed  1.2. Dynamics  1.2.1. Newton's Laws of Motion  1.2.2. Inertia and mass  1.2.3. Force and its types  1.2.4. action and reaction force  1.2.5. Friction and its effects  1.2.6. Coefficient of friction  1.2.7. Circular motion  1.2.8. Centripetal force and centripetal acceleration  1.2.9. Momentum and Impulse  1.2.10. Conservation of momentum  1.2.11. Newton's third law and applications  1.3. Work, Energy and Power  1.3.1. Work done by the force  1.3.2. Work–energy theorem  1.3.3. Kinetic energy  1.3.4. Potential energy  1.3.5. Mechanical energy  1.3.6. Energy Conservation  1.3.7. Power and efficiency  1.3.8. Renewable and non-renewable energy sources  1.4. Gravitational force  1.4.1. Newton's law of universal gravitation  1.4.2. Gravitational field and field strength  1.4.3. Acceleration due to gravity on different planets  1.4.4. Kepler's laws of planetary motion  1.4.5. Orbits and satellites  1.4.6. Weight and apparent weight  1.4.7. Gravitational potential energy
  2. Properties of matter  2.1. States of matter  2.1.1. Solid, liquid and gas  2.1.2. Molecular structure of matter  2.1.3. Intermolecular forces  2.1.4. Plasma and Bose–Einstein condensate  2.2. Pressure  2.2.1. Definition of Pressure  2.2.2. Pressure in liquids  2.2.3. Atmospheric pressure  2.2.4. Pascal's principle  2.2.5. Archimedes' Principle and Buoyancy  2.2.6. Surface tension and capillarity  2.3. Elasticity  2.3.1. Hooke's law  2.3.2. Stress and strain  2.3.3. Elastic Limit and Modulus of Elasticity  2.3.4. Applications of Elasticity
  3. Thermal physics  3.1. heat and temperature  3.1.1. Difference Between Heat and Temperature  3.1.2. Temperature scale  3.1.3. Thermal expansion  3.1.4. Thermal equilibrium  3.2. Heat transfer  3.2.1. Conductivity  3.2.2. Convection  3.2.3. Radiation  3.2.4. Insulation and its applications  3.3. Thermal properties of matter  3.3.1. Specific heat capacity  3.3.2. Latent heat and phase change  3.3.3. Boiling and Melting Point  3.3.4. Heat engines and refrigeration  3.4. Laws of Thermodynamics  3.4.1. Zeroth law of thermodynamics  3.4.2. First law of thermodynamics  3.4.3. Second law of thermodynamics  3.4.4. Carnot cycle
  4. Waves and optics  4.1. Nature and properties of waves  4.1.1. Types of waves in nature and properties of waves  4.1.2. Transverse and longitudinal waves  4.1.3. Wave parameters  4.1.4. Reflection and refraction of waves  4.1.5. Superposition and Interference  4.1.6. Standing Waves and Resonance  4.1.7. Doppler effect  4.2. Sound waves  4.2.1. Characteristics of sound waves  4.2.2. Speed of sound in different mediums  4.2.3. Applications of sound waves  4.2.4. Ultrasound and its uses  4.3. Light Waves and Optics  4.3.1. Nature of light  4.3.2. Reflection of light  4.3.3. Laws of reflection  4.3.4. Mirrors and Image Formation  4.3.5. Refraction of light  4.3.6. Snell's Law  4.3.7. Lenses and Image Formation  4.3.8. Total internal reflection and critical angle  4.3.9. Optical fibre  4.4. Optical Instruments  4.4.1. Microscope  4.4.2. Telescope  4.4.3. Human eye and vision defects  4.4.4. Camera and its working principle
  5. Electricity and Magnetism  5.1. Electrostatics  5.1.1. Electric charge and its properties  5.1.2. Conductors and Insulators  5.1.3. Coulomb's law  5.1.4. Electric field and field lines  5.1.5. Electric potential and potential difference  5.1.6. Capacitors and Capacitance  5.2. Current Electricity  5.2.1. Electric current and its measurement  5.2.2. Ohm's law  5.2.3. Resistance and resistivity  5.2.4. Series and Parallel Circuits  5.2.5. Electric power and energy  5.2.6. Kirchhoff's Laws  5.3. Magnetism and Electromagnetism  5.3.1. Magnetic field and field lines  5.3.2. Magnetic effects of electric current  5.3.3. Electromagnetic induction  5.3.4. Faraday's laws of electromagnetic induction  5.3.5. Transformers and Applications  5.3.6. AC and DC current
  6. Modern Physics  6.1. Nuclear physics  6.1.1. Structure of the atom  6.1.2. Bohr's atomic model  6.1.3. Electron Energy Levels  6.1.4. X-rays and applications  6.2. Radioactivity  6.2.1. Types of radiation  6.2.2. Half-life and radioactive decay  6.2.3. Nuclear reactions and applications  6.2.4. Fission and Fusion  6.3. Quantum physics  6.3.1. Wave–particle duality  6.3.2. Photoelectric effect  6.3.3. Energy quantization  6.3.4. Heisenberg's uncertainty principle
  7. Electronics and Communication  7.1. Semiconductors  7.1.1. Conductors, Insulators and Semiconductors  7.1.2. Diodes and their applications  7.1.3. Transistors and Logic Gates  7.1.4. LEDs and photodiodes  7.2. Communication Systems  7.2.1. Basics of communication  7.2.2. Analog and digital signals  7.2.3. Wireless and optical fibre communication  7.2.4. Radio Waves and Modulation

Grade 10 → Electricity and Magnetism → Electrostatics ↓


Capacitors and Capacitance


Capacitors are essential components in electrical and electronic circuits. To understand capacitors, we must first understand the concept of capacitance, which is a measure of a capacitor's ability to store electrical charge. In this guide, we will explore capacitors, how they work, what capacitance is, and the various applications of capacitors.

What is a capacitor?

A capacitor is a device that stores electrical energy in an electric field. It consists of two conductors separated by a dielectric (an insulating material). When voltage is applied to the conductors, electric current flows, and charge accumulates on the conductors, creating an electric field across the dielectric.

Q = C × V

In the above equation:

  • Q is the charge (in coulombs) stored in the capacitor.
  • C is the capacitance of the capacitor (in farads).
  • V is the voltage (in volts) across the capacitor.

Visual example of a capacitor

The above figure shows a simple capacitor having two parallel conducting plates separated by an insulating material.

Understanding holdings

Capacitance is defined as the ability of a capacitor to store electrical charge per unit voltage. The unit of capacitance is farad (F), which is a large unit. Typically, capacitor values are in microfarads (μF), nanofarads (nF) or picofarads (pF).

The capacitance of a capacitor depends on three main factors:

  1. Area of plates: Larger plate area results in more capacitance, as more amount of charge can be stored.
  2. Distance between plates: Smaller distance between the plates increases the capacitance because the strength of the electric field within the dielectric increases.
  3. Dielectric material: The type of dielectric material between the plates affects the capacitance. Materials with high dielectric constant have high capacitance.

Equation for capacitance

The capacitance C of a parallel-plate capacitor can be calculated using the formula:

C = (ε × A) / d

In this equation:

  • ε is the permittivity of the dielectric material between the plates.
  • A is the area of a plate.
  • d is the distance between the plates.

Working principle of capacitor

Initially, when a voltage is applied to a capacitor, an electric field forms across the dielectric as electrons accumulate on one plate and leave the other. Over time, charge accumulates, and energy is stored as an electrostatic field. When the circuit needs energy, the capacitor can release this stored energy, discharging its stored electric charge.

Visualization of the electric field in a capacitor

The blue line between the plates symbolizes the electric field produced when the capacitor is charged.

Types of capacitors

There are many types of capacitors, each with its own distinct characteristics and uses. Some of the common types are as follows:

  • Ceramic capacitors: Known for their small size and stable electrical properties. Used in high frequency applications.
  • Electrolytic capacitors: Known for their high capacitance values and are suitable for power supply filtering applications.
  • Film capacitors: Known for stability and reliability. Used in audio, power, and high-voltage applications.
  • Tantalum capacitors: Known for their compact size and use in portable devices.

Applications of capacitors

Capacitors play an important role in a variety of electronic circuits and applications, including:

  • Energy storage: Capacitors store energy, and provide power when needed, such as in flash photography.
  • Signal filtering: In audio and signal processing applications, capacitors filter out unwanted frequencies.
  • Power conditioning: Capacitors stabilize voltage and power flow in electronic circuits.
  • Tuning circuits: Capacitors are used with inductors to tune radio and television receivers to specific frequencies.
  • Motor starter: In electric motors, capacitors provide phase shifting for starting torque.

Series and parallel capacitor circuits

Capacitors can be connected in series or parallel arrangements, which affects the total capacitance.

Capacitors in series

When capacitors are connected in series, the total capacitance Ct is given by:

1/Ct = 1/C1 + 1/C2 + 1/C3 + ... + 1/Cn

The total capacitance is less than any single capacitor in series.

Parallel capacitors

When capacitors are connected in parallel, the total capacitance Ct is simply:

Ct = C1 + C2 + C3 + ... + Cn

Total holdings are equal to the sum of all individual holdings.

Summary

Capacitors are important components in physics and engineering, especially in the field of electronics. They store electrical energy, filter signals and stabilize voltages. Understanding capacitance and how capacitors work is crucial for designing and working with modern electronic systems. This guide provides an overview of capacitors, capacitance, and the role of capacitors in various applications. By mastering the concepts of capacitance, appreciating the different types of capacitors, and understanding their applications, you can harness the power of capacitors in practical scenarios.


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