“The Knowledge Library”

Knowledge for All, without Barriers…

An Initiative by: Kausik Chakraborty.

“The Knowledge Library”

Knowledge for All, without Barriers……….
An Initiative by: Kausik Chakraborty.

The Knowledge Library

General Science

WHAT ARE QUANTUM DOTS?

Quantum dots are semiconductor nanocrystals with unique optical and electronic properties that make them valuable for a wide range of applications in various fields, including

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STARS

Introduction The moon completes one rotation around its axis in 29 days and the same time it takes to complete one revolution around the earth.

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SURFACE TENSION

Introduction Surface tension explains why Bubbles are spherical. Water doesn’t spread on some surfaces but forms droplets. Oil and water don’t mix; water wets us

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METHODS OF SEPARATION

  Introduction Threshing: Beating stalks to free grains Winnowing: Separate lighter and heavier components of a mixture by blowing air. Sieving: Separate components of different

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SOUND

Introduction What is Sound? Sound is produced by vibrating objects. Vibrations cause compressions [high pressure] and rarefactions [low pressure]. Sound waves travel through a medium

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FORCE

Introduction This is either contact [friction, muscular] or non-contact [magnetic, electrostatic, gravitational, pressure] Pressure Pressure is inversely related to the area. So smaller the area,

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HEAT

Introduction When a solid is heated the kinetic energy of the molecules is increased and it overcomes the force of attraction of molecules and the

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ELECTRICITY AND CIRCUITS

Conductors and Insulators Conductors –allow electricity to pass through them. Due to free electrons present on their surface. [Metals, Human body] Insulators – Don’t allow electricity to

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CLIMATE

Climate Air moves from a region of high air pressure to low air pressure. Air when heated rises as it becomes lighter. Air expands on

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HORMONES

  Human Hormones     The pituitary gland is an endocrine [ductless] gland. The hormones of the pituitary gland stimulate testes and ovaries to produce their

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CHROMOSOMES

Introduction The male has two chromosomes X and Y, the female has only X chromosomes. During reproduction, if the X and X chromosomes come together then

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ORGANISMS AND ENVIRONMENT

Introduction Ecology – the study of the relationship between organisms and the environment Ecosystems – functional unit of nature encompassing interaction between its biotic and abiotic components.

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BODY JOINTS

  Introduction Ball and Socket joint – The rounded end of one bone fits into the cavity of the other bone. Such a joint allows movement

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SOIL

  Introduction Soil has the following layers: Topsoil or A-Horizon: Humus, the topmost layer, retains water, and provides shelter to organisms B-Horizon: Middle layer, harder and

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ENVIRONMENT

  Introduction Herbs – Plants with green and tender stems and almost no branches. E.g: Tomato – Herb Shrubs – Branches near the base, thin but hard

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WATER

  Introduction 22 March is World water day. UN recommends 50 liters of water per person per day. 2003 was the international year of freshwater

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MIXTURES

Introduction Homogenous mixtures have a uniform composition throughout e.g. salt water and sugar water, tincture alcohol [iodine+alcohol]. Solid solutions like alloys [brass = zinc + copper]

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ELEMENTS

  Introduction Metals are malleable [can be beaten into sheets], ductile [pulled into wires] and conductors of heat and electricity, and sonorous [produce ringing sounds when

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FABRICS

  Introduction    Fabrics like cotton, silk are made of yarns and yarns are made of fibers. Types of Fibers: Natural Fibers: Cotton, jute [plant], silk [cocoon of

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CELLS

  Introduction    Bodies of organisms are made of tiny units called Cells. Cells have an outer boundary called a cell membrane [made up of lipids

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MICRO-ORGANISMS

  Introduction Microorganisms are of four types: bacteria [TB, typhoid, cholera, diphtheria, and plague], algae, protozoa [dysentery, malaria], and fungi. Virus [jaundice] reproduces only inside

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Blood and Constituents

  Introduction     Blood contains a fluid part called plasma. Red blood cells [erythrocytes] have red pigment hemoglobin which binds oxygen and transports it to all cells.

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NUTRITION

Introduction Components of food necessary for the body are called Nutrients. Organisms that prepare food themselves from simple substances are called Autotrophs and animals that take in ready-made

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