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Chapter 5 – Light Energy

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

Have you ever wondered how light is used for food production? Light is easy to understand and helps living beings, including humans, to see, but light is an energy source, and just like all energy, light can move, change direction, and function. In photosynthesis, light energy is converted into chemical energy, where the autotrophs generate carbohydrate molecules. Here, you will learn about light energy and various other aspects of light energy.

Light energy is a kind of kinetic energy that allows people’s eyes to see different light shades. The type of electromagnetic radiation produced by hot objects, such as lasers, lamps, and the sun, are characterized by light travelling in the form of a wave. Light energy is swift and moves faster, with a speed of 186,282 miles per second.

Light includes photons that are minute energy bundles. As the atoms of an object heat up, photons are emitted and produced. The electrons are excited by heat and accumulate extra energy, emitted as a photon, and the material becomes hotter with more photons.

Light has different types of essential properties, and these are as follows:

  • Light rays move in a straight line
  • The travelling speed of light is 3 x 108 m/s, which is much faster than sound
  • Diffraction of light
  • Dispersion of light
  • Reflection of light
  • Refraction of light
  • Polarization of light

Reflection of light occurs as the waves encounter a reflecting surface or its borders, not absorbing the radiation energy while the waves bounce back from the body. When light rays reflect a body, they travel from one transparent medium to another or move through a medium with a frequently altered composition. According to the law of reflection:

  • The incident ray, the reflected ray and the normal to the surface at the point of incidence all lie in the same plane.
  • The angle of incidence is equal to the angle of reflection.

The definition of refraction states that it is a process where the speed of light changes as it passes from a medium to another medium, resulting in light beams’ bending. Refraction of light obeys two of the following laws:

  • The incident ray, the reflected ray and the normal to the surface at the point of incidence all lie in the same plane.
  • The ratio of the sin of the angle of incidence to the sin of the angle of refraction is always constant for a given pair of media and the light of the given wavelength.

One of the simplest examples of refraction is a half-filled glass of water with a pencil. See how the crayon looks normal above the water, but it seems much more significant and curved under the water. It happens as a result of refraction.

A mirror is a reflective plate that springs from light and produces an image or a virtual image. When an object is set before a mirror, it is visible as its reflection in the mirror. The item is the ray source, and the representation consists of the reflected rays. The images are known as real images or composite images based on the relationship between light. A real image is produced when the light rays converge, while virtual pictures arise due to the light rays’ apparent divergence.

Mirrors are of two types, namely a plane mirror and a spherical mirror. A plain reflecting mirror has a flat and smooth reflection, while a spherical mirror or curved mirror is a mirror with a constant curve and a constant curvature radius.

Curved mirrors are mirrors with curved surfaces on one edge. There are two types of curved mirrors, namely convex and concave mirrors. Spherical mirrors with interior surfaces are known as convex mirrors, while spherical mirrors with exterior surfaces are known as concave mirrors.

  1. Convex mirror
    The curved mirror that bulges outward towards the light source is known as a convex mirror or divergent mirror. Convex mirrors reflect light externally, such that these are not used for focusing. These mirror images cannot be projected onto the screen because the image is smaller than the object but grows as the object gets close to the mirror.

  2. Concave mirror
    A concave mirror has a reflective layer recessed within a mirror (away from the incident light). The concave mirror reflects light in a single focus as these are used to focus light. Concave mirrors display varying images according to the distance from the source to the mirror compared to convex mirrors.

 

There are numerous uses of curved mirrors and are listed as follows:

  • Curved surfaces of concave mirrors are used most often in shaving.
  • The ophthalmoscope is composed of a concave mirror and a central hole. The doctor focuses from behind the concave mirror into the narrow spot, and a ray of light is directed to the patient’s pupil.
  • Concave mirrors are often used as reflectors in automotive and motor vehicle lamps, flashlights, train engines.
  • A concentric mirror of 5 metres or more is used as the target in an astronomical telescope.
  • Convex mirrors are used extensively in cars as rear-view mirrors.
  • Convex mirrors are commonly used in the production of magnifying lenses. Two convex mirrors are positioned back-to-back to create a magnifying lens.
  • Massive companies, shops and hospitals use a convex mirror to allow pedestrians to see the corner to deter collisions.
  • Convex mirrors in different locations are often used for safety purposes. It is located in an ATM vicinity, so bank clients can see if someone is behind them.

A variety of technological advances have turned around light over the last century. Optical research has allowed us to develop our knowledge of light energy and its relationships with all sorts of matter.

  1. Why is light considered a source of energy?
    According to Einstein, light has no energy because it has no mass, but how can sunlight heat the planet without energy? In reality, despite no mass, light carries energy through its momentum.
  2. What are the different types of light?
    They are visible rays, infrared rays, X-rays, and UV rays.
  3. Which colour of light has the highest and lowest energy?
    Violet is having the highest while red is having the least amount of energy.
  4. Which phenomenon is responsible for the blue colour of the sky?
    Rayleigh scattering.

Some of the various terms related to curved mirrors are centre of curvature, the radius of curvature, pole, principal axis, aperture, central focus or focal length and focus. At MSVgo, we provide you with easy video lessons to understand the fundamental difference between them and understand them easily. For an in-depth understanding of light energy, you can check out the MSVgo mobile app to get your doubts clear on the go!

High School Physics

  • Alternating Current
  • Atoms
  • Communication Systems
  • Current Electricity
  • Dual nature of Radiation and Matter
  • Electric Charges and Fields
  • Electricity
  • Electromagnetic Induction
  • Electromagnetic Waves
  • Electron Beams and Radioactivity
  • Electrons and Photons
  • Electrostatic Potential and Capacitance
  • Fluid Pressure
  • Force and Acceleration
  • Force And Laws Of Motion
  • Gravitation
  • Internal Energy
  • Kinetic Theory
  • Law of motion
  • Light – Reflection And Refraction
  • Magnetic Effects Of Electric Current
  • Magnetism and Matter
  • Management Of Natural Resources
  • Mechanical properties of Fluids
  • Mechanical properties of Solids
  • Motion
  • Motion in a plane
  • Motion in a straight line
  • Moving Charges and Magnetism
  • Nuclear Energy
  • Nuclei
  • Oscillations
  • Our Environment
  • Paths of Heat
  • Physical world
  • Ray optics and optical instruments
  • Semiconductor Devices
  • Semiconductor Electronics: Materials, Devices and Simple Circuits
  • Simple Machines
  • Sound
  • Sources Of Energy
  • Specific and Latent Heats
  • Spherical Mirrors
  • Static Electricity
  • Systems of Particles and Rotational motion
  • Thermal properties of matter
  • Thermodynamics
  • Units and Measurement
  • Vectors, Scalar Quantities and Elementary Calculus
  • Wave Optics
  • Waves
  • Work, Power and Energy

High School Chemistry

  • Acids, Bases and Salts
  • Alcohols, Phenols and Ethers
  • Aldehydes, Ketones and Carboxylic Acids
  • Aliphatic and Aromatic Hydrocarbons
  • Alkyl and Aryl Halides
  • Amines
  • Analytical Chemistry 
  • Atomic Structure
  • Atoms And Molecules
  • Basic concepts of Chemistry
  • Biomolecules
  • Carbon And Its Compounds
  • Carboxylic acids and Acid Derivatives
  • Chemical Bonding and Molecular Structures
  • Chemical Energetics
  • Chemical Equilibria
  • Chemical Kinetics
  • Chemical Reactions And Equations
  • Chemical Reactions and Their Mechanisms
  • Chemistry in Everyday Life
  • Chemistry of p-Block elements
  • Chemistry of Transition and Inner Transition
  • Classification of Elements
  • Coordination Compounds
  • Cyanide, Isocyanide, Nitro compounds and Amines
  • Electrochemistry
  • Electrolysis
  • Elements, Compounds and Mixtures
  • Environmental Chemistry
  • Equilibrium
  • Ethers and Carbonyl compounds
  • Haloalkanes and Haloarenes
  • Hydrocarbons
  • Hydrogen
  • Ideal solutions
  • Introduction to Organic Chemistry
  • Ionic equilibria
  • Matter
  • Matter Around Us
  • Matter In Our Surroundings
  • Metallurgy
  • Metals And Non-Metals
  • Mole Concept and Stoichiometry
  • Natural Resources
  • Organic Chemistry – Basic Principles
  • Periodic Classification of Elements
  • Physical and Chemical Changes
  • Physical and Chemical Properties of Water
  • Polymers
  • Preparation, Properties and Uses of Compounds
  • Principles and Processes of Isolation of Elements
  • Redox Reactions
  • Relative Molecular Mass and Mole
  • States of Matter
  • Structure Of The Atom
  • Study of Compounds
  • Study of Gas Laws
  • Study of Representative Elements
  • Surface Chemistry
  • The d-block and f-block elements
  • The Gaseous State
  • The p-Block Elements
  • The Periodic Table
  • The s-Block Elements
  • The Solid State
  • Thermodynamics

High School Biology

  • Absorption and Movement of Water in Plants
  • Adolescent Issues
  • Anatomy of Flowering Plants
  • Animal Kingdom
  • Bacteria and Fungi-Friends and Foe
  • Biodiversity and Conservation
  • Biofertilizers
  • Biological Classification
  • Biomedical Engineering
  • Biomolecules
  • Biotechnology and its Applications
  • Biotic Community
  • Body Fluids and Circulation
  • Breathing and Exchange of Gases
  • Cell – Unit of Life
  • Cell Cycle and Cell Division
  • Cell Division and Structure of Chromosomes
  • Cell Reproduction
  • Cellular Respiration
  • Chemical Coordination and Integration
  • Circulation
  • Control And Coordination
  • Crop Improvement
  • Digestion and Absorption
  • Diversity In Living Organisms
  • Ecosystem
  • Environmental Issues
  • Excretory Products and their Elimination
  • Flowering Plants
  • Genes and Chromosomes
  • Health and Diseases
  • Health and Its Significance
  • Heredity And Evolution
  • Heredity and Variation
  • How Do Organisms Reproduce?
  • Human Diseases
  • Human Eye And Colourful World
  • Human Health and Disease
  • Human Population
  • Human Reproduction
  • Hygiene
  • Improvement In Food Resources
  • Integumentary System- Skin
  • Kingdom Fungi
  • Kingdom Monera
  • Kingdom Protista
  • Life Processes
  • Locomotion and Movement
  • Microbes in Human Welfare
  • Mineral Nutrition
  • Molecular Basis of Inheritance
  • Morphology of Flowering Plants
  • Neural Control And Coordination
  • Nutrition in Human Beings
  • Organism and Population
  • Photosynthesis
  • Photosynthesis in Higher Plants
  • Plant Growth and Development
  • Plant Kingdom
  • Pollination and Fertilization
  • Pollution; Sources and its effects
  • Principles of Inheritance and Variation
  • Reproduction and Development in Angiosperms
  • Reproduction in Organisms
  • Reproductive Health
  • Respiration in Human Beings
  • Respiration in Plants
  • Respiratory System
  • Sexual Reproduction in Flowering Plants
  • Strategies for Enhancement in Food Production
  • Structural Organisation in Animals
  • Structural Organisation of the Cell
  • The Endocrine System
  • The Fundamental Unit Of Life
  • The Living World
  • The Nervous System and Sense Organs
  • Tissues
  • Transpiration
  • Transport in Plants

High School Math

  • Algebra – Arithmatic Progressions
  • Algebra – Complex Numbers and Quadratic Equations
  • Algebra – Linear Inequalities
  • Algebra – Pair of Linear Equations in Two Variables
  • Algebra – Polynomials
  • Algebra – Principle of Mathematical Induction
  • Algebra – Quadratic Equations
  • Binomial Theorem
  • Calculus – Applications of Derivatives
  • Calculus – Applications of the Integrals
  • Calculus – Continuity and Differentiability
  • Calculus – Differential Equations
  • Calculus – Integrals
  • Geometry – Area
  • Geometry – Circles
  • Geometry – Conic Sections
  • Geometry – Constructions
  • Geometry – Introduction to Euclid’s Geometry
  • Geometry – Three-dimensional Geometry
  • Geometry – Lines and Angles
  • Geometry – Quadrilaterals
  • Geometry – Straight Lines
  • Geometry – Triangles
  • Linear Programming
  • Matrices and Determinants
  • Mensuration – Areas
  • Mensuration – Surface Areas and Volumes
  • Number Systems
  • Number Systems – Real Numbers
  • Permutations and Combinations
  • Probability
  • Sequence and Series
  • Sets and Functions
  • Statistics 
  • Trignometry – Height and Distance
  • Trignometry – Identities
  • Trignometry – Introduction

Middle School Science

  • Acids, Bases And Salts
  • Air and Its Constituents
  • Basic Biology
  • Body Movements
  • Carbon and Its Compounds
  • Cell – Structure And Functions
  • Changes Around Us
  • Chemical Effects Of Electric Current
  • Chemistry in Your Life
  • Coal And Petroleum
  • Combustion And Flame
  • Components Of Food
  • Conservation Of Plants And Animals
  • Crop Production And Management
  • Electric Current And Its Effects
  • Electricity And Circuits
  • Elements and Compounds
  • Fibre To Fabric
  • Food production and management
  • Force And Pressure
  • Forests: Our Lifeline
  • Friction
  • Fun With Magnets
  • Garbage In, Garbage Out
  • Getting To Know Plants
  • Health and Hygiene
  • Heat
  • Hydrogen
  • Life Processes: Nutrition in Animals and Plants
  • Light, Shadows And Reflections
  • Materials: Metals And Non-Metals
  • Matter and Its States
  • Metals and Non-metals
  • Micro Organisms: Friend And Foe
  • Motion And Measurement Of Distances
  • Motion And Time
  • Nutrition In Animals
  • Nutrition In Plants
  • Organization in Living Things
  • Our Environment
  • Physical And Chemical Changes
  • Pollution and conservation
  • Pollution Of Air And Water
  • Reaching The Age Of Adolescence
  • Reproduction In Animals
  • Reproduction In Plants
  • Respiration In Organisms
  • Rocks and Minerals
  • Separation Of Substances
  • Simple Machines
  • Soil
  • Some Natural Phenomena
  • Sorting Materials Into Groups
  • Sound
  • Stars And The Solar System
  • Structure of Atom
  • Synthetic Fibers And Plastics
  • The Living Organisms And Their Surroundings
  • Transfer of Heat
  • Transformation of Substances
  • Transportation In Animals And Plants
  • Universe
  • Waste-water Story
  • Water: A Precious Resource
  • Weather, Climate And Adaptations Of Animals To Climate
  • Winds, Storms And Cyclones

Middle School Math

  • Addition
  • Area and Its Boundary
  • Boxes and Sketches
  • Data Handling
  • Fun With Numbers
  • Heavy and Light
  • How Many
  • Long And Short
  • Mapping
  • Measurement
  • Money
  • Multiplication and Factors
  • Multiply and Divide
  • Numbers
  • Parts and Wholes
  • Pattern Recognition
  • Patterns
  • Play With Patterns
  • Rupees And Paise
  • Shapes And Angles
  • Shapes And Designs
  • Shapes and Space
  • Similarity
  • Smart Charts
  • Squares
  • Subtraction
  • Tables And Shares
  • Tenths and Hundredths
  • Time
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