# Chapter 16 – Light

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

Introduction

Have you ever thought of a life where there is no light? A world that is dark and does let us appreciate the beauty of nature? If not for the light that the Sun blesses us with, the sense of sight too has no meaning to it.

It, therefore, becomes important that you understand the concept of light and its importance in nature.

#### What makes light visible?

When light reflects from a surface, that surface becomes visible to the human eye.

Let us learn how a ray of light makes things visible by understanding the concepts of Incident ray, Reflected ray, and a Normal.

Case: Imagine a mirror placed on a plane surface opposite to which, a black screen is placed with a small gap in it. Now position a torch (as our source of light) in such a manner that the ray of light coming out of the torch will pass through the gap in the black screen and fall on a point on the mirror.

Incident ray: The ray of light that falls on the mirror is called the incident ray.

Reflected ray: The same ray of light when it reflects back from the mirror surface is called the reflected ray.

Normal: If we draw a straight line at 90° perpendicular to the mirror surface at the point where the light falls on the mirror, this straight line is called Normal.

#### Laws of reflection

To understand the laws of reflection, you must first understand the following terms:

Angle of incidence: The angle between the Normal and the incident ray is the angle of incidence.

Angle of reflection: The angle between the Normal and the reflected ray is the angle of reflection.

1)   First law of reflection: The angle of incidence is always equal to the angle of reflection. Even If you change the angle of incidence, the angle formed by the reflected ray will still be equal to that formed by the incident ray.

2)   Second law of reflection: The incident ray, the Normal (at the incidence point), and the reflected ray all lie in the same plane always. If you experiment by adding a break in the plane where the incident ray and Normal are present, it will result in the formation of a new plane. Due to this new plane, the reflected ray is not visible, thus proving the second law of reflection.

Due to this new plane, the reflected ray is not visible, thus proving the second law of reflection.

#### Regular and Diffused reflection

Reflection depends on the surface of reflection. If the surface of reflection is smooth like that of a mirror, the reflection of light is called regular reflection.

If the reflection surface is irregular (such as the surface of the moon), the reflection of light is called irregular or diffused reflection.

#### Reflected light can be reflected again

Imagine having more than one mirror at any angle to each other or parallel. This will lead to multiple images from the same light, which tells us that reflected light can be reflected again.

This principle is used in Kaleidoscope.

#### Sunlight: White or Coloured?

The sunlight is made of seven distinct colours. You have already studied them in class VII with the concept of VIBGYOR, the colours of sunlight.

When light passes through water and mirror or through a prism, it splits into its individual colours. This phenomenon is seen in a rainbow.

#### What is inside our eyes?

The reflected light can be seen only when it enters our eyes. Being one of the most important sensory organs, you must understand the structure of eyes.

Within the outer tough white layer, there is a transparent inner layer called cornea. It is behind the cornea that we can find the muscular structure called iris that hosts the pupil. The colour of the eyes is decided by the iris. Behind the iris is the lens which monitors the amount of light that enters the eyes and focuses the light on the inner retina. It is the retina that passes signals to the brain via its numerous neural connections, thus forming images in the eyes.

#### How can we take care of our eyes?

Nature has protected our eyes by giving it eyelids. But we must take special care of our eyes by these simple practices:

• Frequent washing of eyes.
• Using spectacles to protect eyes from foreign bodies.
• Ensuring moderate amounts of sunlight enters our eye, not too much or too little.
• Reading from a safe distance.

Visually impaired persons can read and write

People with limited to no vision can also read and write with external help. Their other senses get sharper too. Visually impaired people can read and write with the following assistance:

1)     Lenses such as contact, bifocal, etc

2)     Visual, tactual, auditory, and electronic aids.

Braille system

It is a tactual aid developed by Louis Braille for visually impaired people. It consists of a pattern of dots that represent letters and words. These patterns are embossed on sheets so that visually challenged people can recognize words by touching them.

#### FAQs

1) What is light?

Light is an underrated gift of nature without which, everything will be black and colours will not be recognized.

2) What is light called?

It is also referred to as electromagnetic waves.

3) What are the properties of light?

The important properties of light are: it travels in a straight line, the speed of light is faster than sound, and the phenomenon of reflection of light.

4) What are the 7 types of light?

The white light is made up of the following 7 colours: Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

5) Is white light just white?

No, white light when reflected through a prism splits into its 7 colours otherwise not visible to naked eye.

The topic of Light can be understood better by referring to MSVgo, a learning app. It is a video learning app on Maths and Science for students from class 6th to 12th. Check out the app and understand the concept of Light through its interactive animations and explanations.

### 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
Please switch to portrait mode
for the best experience.