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 → Magnetism and Electromagnetism ↓


Transformers and Applications


Transformers play a vital role in the world of electricity and magnetism. They help us manage and use electrical energy efficiently. In this section, we will explore the basic principles behind transformers, how they work, and their various applications. We will use simple language and examples so that class 10 students can understand these concepts better.

What is a transformer?

A transformer is an electrical device used to change the voltage of alternating current (AC). It can increase (step up) or decrease (step down) the voltage. Transformers work on the principle of electromagnetic induction.

Transformers contain two or more coils of wire called windings. These coils are wrapped around a common core that is usually made of iron. The primary winding is connected to the input voltage, and the secondary winding is connected to the output load.

How does a transformer work?

The working principle of a transformer is based on Faraday's law of electromagnetic induction. Let's understand it step by step.

When AC voltage is applied to the primary winding, it creates a varying magnetic field around it. This magnetic field induces voltage in the secondary winding due to electromagnetic induction. The induced voltage in the secondary winding depends on the number of turns in both primary and secondary winding.

    VP / VS = NP / NS

Here, Vp is the primary voltage, Vs is the secondary voltage, Np is the number of turns in the primary winding, and Ns is the number of turns in the secondary winding. This formula helps us to determine the output voltage of the transformer.

Types of transformers

Step-up transformer

Step-up transformers increase the voltage from the primary side to the secondary side. This type of transformer has more turns in the secondary winding than in the primary winding. Step-up transformers are used in power plants where electricity is generated at low voltage but needs to be transmitted over long distances at high voltage to reduce power losses.

Step-down transformer

A step-down transformer reduces the voltage from the primary side to the secondary side. In this case, the primary winding has more turns than the secondary winding. Step-down transformers are commonly found in everyday applications where high-voltage electricity from power lines needs to be reduced to a safe level for use in homes and industries.

Applications of transformer

Power distribution

The most important use of transformers is in power distribution. Electricity is usually generated at power stations at a certain voltage level, such as 11kV or 33kV. This electricity needs to be transmitted over long distances. Higher voltage reduces energy losses during transmission. This is where step-up transformers come in handy.

Near our homes and businesses, step-down transformers reduce the voltage to safer levels, such as 240V or 120V, making it usable for everyday appliances.

Mobile phone charger

Have you ever charged your mobile phone? If yes, you have used a small transformer called an adapter. This type of transformer converts the high voltage from your power outlet to a lower voltage suitable for your device.

Welding machine

Welding machines use step-down transformers to reduce the voltage while simultaneously increasing the current. This high current is necessary to melt the metals and join them together in the welding process.

Visualization of transformer principles

Let's look at a simple example of a transformer core and coils:

This illustration shows the basic structure of a transformer with two windings. The gray rectangles represent the core, while the red and blue circles represent the primary and secondary windings, respectively.

Factors affecting the efficiency of a transformer

Transformer efficiency refers to how well a transformer transfers power from the primary to the secondary winding. Although transformers are highly efficient devices, certain factors can cause losses including:

Core losses

These are caused by the alternating magnetic field in the core. Core losses include hysteresis losses and eddy current losses. Using materials that are good at conducting magnetic fields, such as silicon steel, can help reduce these losses.

Loss of copper

Copper losses occur due to resistance in the windings. When current flows through the windings, heat is generated due to the resistance and power losses occur. Thicker and high-quality copper wires can reduce these losses.

Mathematical example: Calculate the output voltage

Consider a transformer having a primary winding of 100 turns and a secondary winding of 50 turns. If an AC voltage of 200V is applied to the primary winding, what will be the output voltage at the secondary winding?

Use of the transformer formula:

    VP / VS = NP / NS

Plugging in the known values:

    200 / Vs = 100 / 50

Solve for Vs:

    VS = (200 * 50) / 100 = 100V

Thus, the output voltage will be 100V.

Conclusion

Transformers are critical components in modern power systems. Their ability to efficiently transfer electrical energy from one circuit to another and to change voltage levels makes them indispensable in power distribution and a variety of everyday applications. By understanding their structure and function, we gain insight into how electricity is managed and used effectively.


Grade 10 → 5.3.5


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Faraday's laws of electromagnetic induction
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Transformers and Applications

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