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 → Waves and optics → Nature and properties of waves ↓


Reflection and refraction of waves


Introduction to waves

Waves are disturbances that travel through a medium and transfer energy from one point to another. They can be found in various forms such as light waves, sound waves and water waves. Understanding how these waves behave is important in fields such as physics, optics and engineering.

Basic properties of waves

To understand how waves reflect and refract, it is necessary to know some basic properties:

  • Wavelength: The distance between successive crests or troughs in a wave.
  • Frequency: The number of waves passing a fixed point in one second, measured in hertz (Hz).
  • Amplitude: The height of the wave crest or the depth of the trough from the rest position.
  • Speed: How fast the wave travels through the medium.

What is reflection of waves?

Reflection of waves occurs when a wave hits a boundary or surface and returns to the medium from which it came. Just like a ball bounces back after hitting a wall, waves also reflect from surfaces according to specific rules.

Law of reflection

The law of reflection states that the angle of incidence is equal to the angle of reflection. This means that the angle at which the incoming wave hits the surface is the same as the angle at which it reflects away.

Angle of Incidence (i) = Angle of Reflection (r)

Consider a wave striking a flat mirror. The incoming wave is called the incident wave, and the wave that returns is called the reflected wave. The imaginary line perpendicular to the point where the wave strikes the mirror is called the normal line.

mirror Incident wave Reflected wave normal line

Examples of reflection

1. Sound Waves: Echo is a good example of sound wave reflection. When you shout in a canyon, the sound waves reflect off the walls, allowing you to hear your voice again.

2. Light waves: Mirrors reflect light waves. This is why we can see our images in them. Cameras and telescopes also use this principle to focus light.

3. Water Waves: Water waves reflect on the shore of a pond or lake and create patterns that interact with the incoming waves.

What is refraction of waves?

Refraction occurs when a wave changes direction as it enters from one medium to another. This change in direction is caused by a change in the speed of the wave. Refraction is responsible for many interesting phenomena, such as the bending of light as it enters water.

Understanding Snell's law

Snell's law describes how the angle of incidence and the angle of refraction are related when a wave passes from one medium to another.

n1 * sin(θ1) = n2 * sin(θ2)

Here, n1 and n2 are the refractive indices of the first and second medium, respectively, and θ1 and θ2 are the angles of incidence and refraction.

Examples of refraction

1. Bending of light: When light enters water from air, it slows down and bends toward the normal line. As a result, objects underwater appear closer to the surface than they really are.

Air Water Incident wave Refracted wave

2. Mirages: On hot days, the ground heats up the air above it, which bends light waves. This makes distant objects appear distorted or appear to be in places where they aren't, creating mirages.

Understanding optical density

Optical density refers to how much a medium can slow down light waves. A medium with a higher optical density has a higher refractive index and slows down light more than a medium with a lower optical density.

For example, light travels faster through air than through glass, which means that air has a lower optical density than glass.

Critical angle and total internal reflection

When light travels from a denser medium to a less dense medium, it refracts away from the normal line. If the angle of incidence is greater than a particular angle called the critical angle, no refraction occurs. Instead, the light reflects back into the denser medium, which is known as total internal reflection.

The critical angle can be calculated using the following formula:

Critical Angle (θc) = sin^(-1) (n2/n1)

where n1 is the refractive index of the denser medium, and n2 is the refractive index of the less dense medium.

Applications in everyday life

Reflection and refraction are not just theoretical concepts; they also have practical applications in daily life:

  • Optical instruments: Microscopes, cameras, and telescopes use lenses to refract light, making magnification and focusing of images possible.
  • Fiber optics: Fiber optics technology uses total internal reflection to transmit data over long distances with minimal loss.
  • Glasses: Glasses lenses help correct vision by refracting light, and focusing images accurately on the retina.
  • Rainbow: Rainbows are caused by the refraction, dispersion and reflection of sunlight inside raindrops.

Conclusion

Understanding the reflection and refraction of waves provides a deeper insight into the nature of how waves behave. These principles help explain a wide range of natural phenomena and are fundamental to advancing technology in optics and communications.


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Reflection and refraction of waves

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