Hello friends, how are you doing? I hope you are doing great! Friends, I am Dheeraj Sahni and welcome to my website - www.mathshindi.com. On this website, you learn complex topics related to maths in an easy and interesting way.
Friends, today I am going to explain to you - "Square and Square Root"
So without wasting time, Let's get started...
Before we understand - What the square root is. We have to understand - What the square is.
What is Square?
"A square is a number which is obtained by multiplying the given number by itself, for example, square of 2 is 2 x 2, means 4."
Similarly,
Square of 1 is 1 x 1, which means 1. Square of 3 is 3 x 3, which means 9. Square of 4 is 4 x 4, which means 16. Square of 5 is 5 x 5, which means 25. Square of 6 is 6 x 6, which means 36. Square of 7 is 7 x 7, which means 49. Square of 8 is 8 x 8, which means 64. Square of 9 is 9 x 9, which means 81. Square of 10 is 10 x 10, which means 100, and so on.
In the same way, you can find the square of any Natural number!
Square of 0 is 0 x 0, which means 0. Square of -5 is (-5) x (-5), which means 25. Square of 1/2 is (1/2) x (1/2), which means 1/4. Square of √3 is √3 x √3, which means 3. Square of 0.25 is 0.25 x 0.25, which means 0.0625. Square of (2 + 3i) is (2 + 3i) x (2 + 3i), which means (4 - 9 + 12i), which means (-5 + 12i).
In the same way, you can find the square of any number either it is a Real number or a Complex number! "Symbolically we represent 'square' by '2' writing it at the top-right side of the number whose square is to be found in a comparatively smaller size."
In this way, we represent the sentence 'Square of 1 or 1 squared' by '12'.
Now the above examples can be written as follow:
1 squared = 12 = 1 x 1 = 1 3 squared = 32 = 3 x 3 = 9 4 squared = 42 = 4 x 4 = 16 5 squared = 52 = 5 x 5 = 25 6 squared = 62 = 6 x 6 = 36 7 squared = 72 = 7 x 7 = 49 8 squared = 82 = 8 x 8 = 64 9 squared = 92 = 9 x 9 = 81 10 squared = 102 = 10 x 10 = 100
I hope, now you have a better understanding of - What the square is.
Now, let's move on to our main topic - What the square root is.
What is Square Root?
"The square root is just opposite of what square is. Finding the square root of a number is finding a number which when multiplied by itself, gives the given number. For example, square root 9 is 3 because when we multiply 3 by itself, i.e. 3 x 3, gives 9."
Similarly,
Square root of 0 is 0 because 0 x 0 = 0. Square root of 1 is 1 because 1 x 1 = 1. Square root of 4 is 2 because 2 x 2 = 4. Square root of 16 is 4 because 4 x 4 = 16. Square root of 25 is 5 because 5 x 5 = 25. Square root of 36 is 6 because 6 x 6 = 36. Square root of 49 is 7 because 7 x 7 = 49. Square root of 64 is 8 because 8 x 8 = 64. Square root of 81 is 9 because 9 x 9 = 81. Square root of 100 is 10 because 10 x 10 = 100, etc.
"Symbolically we represent 'square root' by '√' writing it just before the number whose square root is to be found."
In this way, we represent the sentence 'Square root of 1 or square root 1' by '√1'.
Now the above examples can be written as follow:
√0 = 0 because 0 x 0 = 0 √1 = 1 because 1 x 1 = 1 √4 = 2 because 2 x 2 = 4 √25 = 5 because 5 x 5 = 25 √36 = 6 because 6 x 6 = 36 √49 = 7 because 7 x 7 = 49 √64 = 8 because 8 x 8 = 64 √81 = 9 because 9 x 9 = 81 √100 = 10 because 10 x 10 = 100
I hope, now you have a better understanding of - What the square root is.
Now I will ask a question and you have to give the answer, Ok! So, here is the question - What is the square root of 10? (Think about it!)
Can you able to find the answer? Can you able to find a number which when multiplied by itself, gives 10? I think you will not have found that number. Am I right? If I am right, now you will be thinking that - 'We cannot find the square root of 10. The square root of 10 does not exist.'
Well, I want to tell you, this is not so! We can find the square root of any Natural number. And not only of Natural numbers; we can find the square root of any Whole number, Non-negativeInteger, Non-negative Rational number, Non-negative Irrational number, Non-negative Real number.
Note:The square root of any negative number whether it is negativeInteger or negative Rational number or negative Irrational number or negative Real number, does not exist. They are Imaginary numbers (or Complex numbers).
Now, 10 is a Natural number (It is also a Whole number, a non-negative Integer, a non-negative Rational number, a non-negative real number.) So we can find out the square root of 10. Now you may be thinking that how can we find the square root of 10. How can we find the number which when multiplied by itself, gives 10? (You may be excited to know that. I think!)
There are methods and some short tricks for finding out the square root of imperfect square numbers or non-perfect square numbers like 10, 7, 11, 21, etc. A perfect square number is that whose square root is a Whole number. If I say in simple words, the squares of all Whole numbers are the perfect square numbers. For example: 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, etc. are perfect squares numbers or just perfect squares.
Actually, there are three main methods to find out the square root of the given number:
1. Square root by Prime Factorisation Method 2. Square root by Estimation Method 3. Square root by Long Division Method
In spite of the above three main methods, there are some more methods that are used for finding the square root of a number, such as the Square root by Vedic Method etc.
The vast space containing our earth and all other heavenly bodies, also called celestial bodies, constitutes the universe. These celestial bodies that form the universe include galaxies, stars, and comets along with the other members of the solar system, v.i.z, planets, asteroids, meteors, and satellites.
Our solar system
In your observations, you will identify a particular pattern of their positions in the sky. It is, for this reason, that, in ancient times when there were no watches or clocks, stars were used in keeping time at night and in finding the directions. The knowledge of their positions was of great value to navigators or travellers at night time.
On a clear night, when the moon is not visible in the sky, go out in open ground or on to the roof of your house and look at the sky. There you see small twinkling luminous objects, called stars. Identify a particular group of stars, locate this position with respect to your position. Continue your observation for seven consecutive days. Record your observations.
Group Discussion
How will you estimate the time if you do not have any clock or watch at the daytime? Discuss with your friends and write a note on the advantages and limitations of the method discussed.
When you look in the sky at night, you see the stars that are twinkling luminous bodies and other celestial bodies that do not twinkle but are just visible to you. These celestial bodies are planets, asteroids, satellites, meteors or shooting stars. Let us learn about these different celestial bodies.
Stars
Stars are the luminous celestial bodies that emit both light and heat like the sun. The sun is also a star
Stars
that appears bigger and brighter being the nearest star to the earth. Alpha Centauri which is the second nearest star to the earth is at a distance of 4.3 light years from the earth. A light year is a large multiple unit of measurement. It is equal to the distance travelled by light in 1 year at the speed of
3ｘ10⁸ m/s or 3ｘ10⁵ km/s.
To convert a light year into metres or kilometres, let us first convert a year into seconds.
1 year = 365ｘ24ｘ60ｘ60 s
= 365ｘ86400 s
= 31536000 s
You know, Speed = Distance / Time
or, Distance = SpeedｘTime
Therefore, Distance = 3ｘ10⁸ m/sｘ31536000 s
= 9.46ｘ10⁵ m or 9.46ｘ10¹² km
In the sky, stars appear stationary but they are not. There are moving away from each other based on the Big Bang Theory that you will learn in your higher classes. They simply look stationary to you because of the large distances they are from the earth. One needs years to understand their increasing distances.
You realized that stars you had identified moved from east to west during the course of your observation. It happened because the earth's surface you were standing on was rotating from west to east on its rotational axis.
It is because of this that the sun, which you now know is a star, rises in the east and sets in the west. There is only one star named Pole star or Polaris or Dhruv Tara that does not appear to move from the earth's surface. It appears stationary because of its location on the earth's rotational axis in the northern hemisphere. It is a member of constellation Ursa Minor about which you will learn in the next section.
Group of Stars
There are two groups of stars in the universe. These are:
1. Galaxies 2. Constellations
Galaxies: A galaxy is a building block of the universe. It is described as a vast system of billions of stars along with a large number of gas clouds, mainly hydrogen gas and dust. The universe is of about 100 billion galaxies and each galaxy is further constituted of the same number of stars, i.e. 100 billion stars, such that the whole universe is constituted of about 10²² stars. This vast number of galaxies in the universe has been classified into three types based on their shapes. These are:
The spiral galaxies are spiral or oval shaped, while the irregular galaxies do not have any definite
Spiral galaxy
shape. The spiral galaxies are the largest of the three types and the elliptical ones are the brightest. There is only a very small percentage of irregular galaxies that are known to us.
The galaxy we live is called, the Milky Way or 'Akash Ganga' because in a clear night sky our galaxy appears as a white band of stars faintly whitening the sky from north to south like a stream or river of light running from one corner to another.
Irregular Galaxy
Constellations: A constellation is a group of a limited number of stars that appear in a closed group to form a recognizable pattern or shape. There are 88 constellations known, called 'Nakshatra' by our ancestors. Each constellation has been assigned a name based on an object, an animal or a human being. Some constellations are:
Ursa Major (Great Bear): In Hindi, it is called Saptarshi because of the seven stars, it consists of.
These seven stars are so arranged that they form a pattern resembling a bear. The three stars in the row represent the tail of the bear and the quadrangle of four stars represents the body of the bear. The constellation is easily visible in the northern sky in the months of July and August.
Ursa Minor (Little Bear): In Hindi, it is called Laghu Saptarshi because it follows the same pattern as the Ursa Major but is smaller in size. This constellation is of importance because the pole star about which you have read earlier is one of its members, Hence, in Hindu mythology, it is also called 'Dhruv Matsya'. The pole star in the Ursa Minor can easily be identified either by identifying the Ursa Minor itself or with help of two pointer stars of Ursa Minor that always points to Pole star.
Orion (Hunter or Mriga or Vyadha): It resembles the structure of a hunter. It is easily visible
during the winter season. It consists of seven bright stars. The four out of these seven stars are arranged in the form of a quadrangle. One of the largest of stars, Betelgeuse, is situated in one corner while on the opposite corner is the star called Rigel and the other three appear to be on a straight line in the middle of it.
Orion
Taurus (Bull or Vrish): It resembles the shape of a bull. It is easily visible in the winter season. The pattern of arrangement shows the front half part of a bull with horns.
Taurus
Libra (Tula or Tarazu): It resembles the shape of a simple physical balance. It is easily visible in the winter season. It comprises of four brightest are arranged in the form of a quadrangle, the upper two stars represent the arm of balance while the lower two represent the pan of the balance.
Scorpio (Vrashchika): It resembles the shape of Scorpion. It is easily visible in the summer season. The pattern that consists of seven stars represents a scorpion with tail and pincers.
Scorpio
Solar System
It is a system of eight planets revolving around the sun in specific orbits along with their satellites. It also includes asteroids, meteors, and comets that revolve around with the sun in the centre.
Our Solar System
Note: Until recently 2006, Pluto was considered as the farthest planet of the solar system. In an International Conference of Renowned astronomers, it was decided not to include Pluto in the list of planets because of its small size and distance from the sun.
Sun: It is a medium-size star of average brightness about 1.5ｘ10⁸ kilometre from the earth's surface.
It has a group of eight planets revolving around it.
Sun
Planets: On a clear night when you look at the sky, some celestial objects do not twinkle. These celestial objects are called planets. The planets appear bright like stars only because they reflect the sunlight falling on them.
There are eight planets in our solar system. These eight planets have been group into two types as terrestrial planets and jovian planets.
Terrestrial planets: The first four planets, the nearest to the sun have been group as terrestrial planets. These planets have a rocky crust like earth, a thin atmosphere and have neither no or few numbers of satellites (moons).
Jovian planets: This planet lack the rocky crust. They are gaseous with a ring and many satellites.
The sun compared to earth is very big with its diameter about 100 times the diameter of earth and mass about a million times the mass of earth. It is not a solid body like the earth but it is a sphere of hot gases, mainly hydrogen and helium. These gases are responsible for the emission of a tremendous amount of energy from the sun by the nuclear fusion of hydrogen into helium that generates a temperature of 6000º C at the surface of the sun. You will study about this in detail and your higher classes.
Almost all the celestial objects you see in space reflects the light of the sun falling on them. It is the bright sunlight that unables you to see stars during the day, despite their presence in space.
Different Planets of Solar System
Planets are comparatively near to the earth's surface and revolve round the sun in specific orbits. Some planets possess natural satellites.
Let us study about the eight planets of the solar system.
Mercury planet
Mercury: It is called Buddha in Hindi. It is the nearest planet to the sun. When viewed from the earth, despite not being a star, it appears as the morning star in the east, mostly in the months of September and October just before sunrise and as an evening star in the west, soon after sunset in the months of March and April. It is a very hot planet because of its closeness to the sun. It bears many similarities with the moon in size, mass, and lack of atmosphere and having a rocky and mountainous crust.
Venus planet
Venus: It is called Shukra in Hindi. It is the second planet in terms of distance from the sun, with almost the same size and mass of about 4/5 times of the mass of earth. When viewed from earth it appears as the brightest celestial body in the universe, at night time other than the moon. It appears bright because of its close to the earth and its ability to reflect almost 75% of the sunlight falling on the earth's surface. Venus is also called the early morning star or late evening start because of its clear visibility in the eastern sky before sunrise and in the western sky after sunset. Venus, like mercury, has no satellite, but unlike mercury has its own atmosphere which is rich in gases such as carbon dioxide. This gas, because of the greenhouse effect which you will study in your higher classes, results in Venus becoming the hottest planet of all the nine planets.
Earth: It is called Prithvi in Hindi. It is the third planet in terms of distance from the sun with a single natural satellite called the moon. The earth, when viewed from the outer space, appears bluish-green because of its reflection of light from the water and the land surface. The earth is a peculiar planet because of its ability to allow the origin, evolution, and sustenance of life. The various factors that helped the earth to achieve this include:
1. Presence of all essential elements such as nitrogen, carbon dioxide, and oxygen in its atmosphere.
2. Presence of liquid water in the ocean, rivers, lakes, and ponds.
3. Presence of a protective layer of ozone that prevents harmful radiations such as ultraviolet radiation to enter in the earth's atmosphere.
4. Presence of appropriate temperature conditions required for the sustenance of life because of greenhouse gases such as CO₂ and CH₄ in the earth's atmosphere.
Earth
The earth, as a planet, shows two types of motion called rotational motion and revolutionary motion.
(a) Rotational motion: The earth rotates on its rotational axis that passes through the North pole and the South Pole despite the fact that it is tilted along its own axis. It completes one rotation in 23 hours 56 minutes and 41 seconds from west to east. It is the rotational motion of earth that results in day and night bringing one part of the earth in front of the sun and simultaneously, taking the other part behind to bring darkness or night, behind its own shadow.
Rotational motion of the Earth
(b) Revolution motion: It is the second motion shown by the earth. In this motion, the earth revolves round the sun and its specific orbit that it completes in 365.25 days. This time period is called a year. It is because of the fact that the earth completes its one revolution in 365.25 days, every fourth year is a leap year having 366 days.
Revolution motion of the Earth
The tilting of the earth along its rotational axis and its revolution round the sun bring changes in its position with respect to the sun to help bring seasonal changes you experience throughout the year and also the difference in the seasonal changes experienced in the northern and the southern hemisphere. When the southern hemisphere is tilted towards the sun, it is summer there but winter in the northern hemisphere and vice versa. The seasons of spring and autumn occur when the earth is in between the two extreme positions of its tilt towards the sun.
Important dates in a year caused because of the revolution of the earth round the sun: The earth revolves round the sun but being tilted at its own axis rotational axis, few days of the year have their own significance. These days are:
(i) 21st June: When the North pole is inclined towards the sun, days are longer than nights. The north pole experiences a day of 24 hours and the South pole experiences a night of 24 hours. The position of the earth is called summer solstice.
(ii) 22nd December: When it is winter in the Northern hemisphere and summer in the southern hemisphere, the day length is the longest in the southern hemisphere and the shortest in the northern hemisphere. The position of the earth is called winter solstice.
(iii) 21st March and 23rd September: These are days when the length of day and night is equal in both hemispheres such that the seasons are either autumn or spring.
Mars: It is called Mangal in Hindi. It is the fourth and the last of terrestrial planets of the solar system with two natural satellites called Phobos and Deimos. It is slightly more than half of the earth in diameter but is one-tenth in mass to the mass of the earth. It is a cold planet with a very thin atmosphere containing traces of gases like carbon dioxide, nitrogen, hydrogen, and oxygen. The oxygen present is too little to support life. The planet Mars from distance appears reddish in colour, hence it is also called the Red planet. It is visible from the earth for the most part of the year but the best time to observe is when it is opposite to the sun's position with respect to the earth.
Recently, in the last decade, the astronomers have happened to notice some changes on Mars's surface that have made them think of the presence of water and life in some form on Mars. However, so for all the efforts have gone in vain although the investigations are still in progress.
Jupiter: It is called Brahspati in Hindi. It is the first of the jovian planets, fifth in distance from the sun and the largest of all the planets of the solar system. It is composed mainly of hydrogen and helium gases along with other gases such as methane and ammonia found in crystalline form.
Jupiter
In brightness, it comes next to mercury and venus. When observed with a telescope, it appears very colourful with the faint ring around it. The 'Red Spot' developed because of some long-lasting storm in its atmosphere, is its characteristic feature. The astronomers so for believe the Jupiter to have 28 satellites.
Saturn: It is called Shani in Hindi. It is almost similar to Jupiter in size, mass, and composition but is more cooler owing to increased distance from the sun to the sixth planet. The planet is characterized by the presence of three distinct rings along with many faint rings around it. It is known to have 30 natural satellites.
Saturn
Uranus: William Herchel in 1781 discovered Uranus. It is different from all other planets of the solar system as it rotates from east to west on its rotational axis, unlike other planets which rotate west to east. It is a very cold planet with 21 natural satellites and an atmosphere consisting of hydrogen, helium, and methane.
Uranus
Neptune: The last planet of the solar system was discovered by U.J. Leverier, who after the discovery of Uranus, on the basis of size calculations, predicted the presence of Neptune and materialized it. It is almost the same as Uranus in size and atmosphere, being very cold with a surface temperature of -190º C.
Neptune
Pluto
Note:Pluto has been stripped off its status as a planet of the solar system on 24 August 2006, when scientists redefined 'planet'. Now our solar system has eight planets only.
Moon is the natural satellite of the Earth. It appears to be the brightest celestial body other than the sun. Moon, being a satellite, revolves round the earth as the earth revolves around the sun. It is the revolution of moon around the earth that results in phases of the moon. The earth revolves round the sun and the moon revolves round the earth, therefore, it is natural for the moon's shadow to form on earth or the earth's shadow to fall on the moon. The shadow of earth or moon results in lunar and solar eclipses, you have studied in the previous class. The days on the basis of the moon's position with respect to the sun and the earth have been classified as full moon day and new moon day.
Moon
Full moon day (Purnima): It is the day when the earth lies between the sun and the moon making the full face of the moon visible.
Full moon day
New moon day (Amavasya): It is the day when sunlight falls on that side of the moon which is invisible, so you cannot see the moon.
New moon day
Between the full moon day and the new moon day, you always happened to see a part of the moon, small or big which is called the crescent of the moon. The different phases of the crescent moon have different shapes. From the new moon day until full moon day it increases and then, after full moon day, until next new moon day, it continuously reduces.
Other Members of the Solar System
The solar system along with sun, planets and their natural satellites contains some other celestial bodies also. The celestial bodies are asteroids, meteors, and comets.
Asteroid
Asteroids: There is a large gap between the orbits of Mars and Jupiter. In 1801, Guiseppe Piazza discovered the presence of small planets like the bodies of rock and metal revolving round the sun between these orbits of Mars and Jupiter. It is these small planets like bodies that are called asteroids. It is believed that because of the reasons unknown till date, at the time of the origin of the solar system, these asteroids had failed to assemble into a planet. It is considered so because each asteroid irrespective of its size, has its own orbit to reverse the like a planet. The biggest of the asteroid to be observed is Ceres, about 700 km in diameter.
Asteroid
Meteor
Meteors: They are innumerable is small rock-like structures that revolve round the sun but, sometimes, one of them under the earth's gravitational pull happens to enter the earth's atmosphere where it gets heated up by friction posed by air. The heat generated is so high that it makes them glow and evaporate in atmospheric air within a short time. This is why they appear as a streak of light in the atmosphere for a short time, hence, called shooting star, despite not being a star.
However, sometimes it happens that a meteor, your after entering the earth's atmosphere, failed to evaporate completely being too big, i.e. it survives the atmospheric friction to land on the earth's surface in the form of small rocks or big rocks which create the craters. Such craters are clearly visible on the surface of the moon as it has no atmosphere to oppose the fall of meteors. These meteors that land in solid form on earth's surface are called meteorite.
The ground hit by a meteor (meteorite), Place: Arizona
Comet
Comet: The orbit of Neptune, the last planet of the solar system, is not the end of the solar system. There are small celestial bodies called comets which, with highly elliptical orbits, extend beyond Neptune's orbit to revolve round the sun. A comet, being small and at large distance, is mostly invisible. It becomes visible only when it approaches the sun in its orbit, in the form of a structure having head and tail. The sun rays make the gases in them glow and expand away from the sun will the solid part of the comet remains in the orbit. Comets, like planets, have a specific period of revolution round the sun, for example, Halley's Comet, named after Edmund Halley, last seen in 1986, has a revolution period of 76 years.
Satellites (Natural and Artificial): A heavenly body that revolves around a planet in its orbit is called a satellite, such as a moon is the natural satellite of the earth. The other planets in the solar system also have their own satellites with Saturn having the maximum number of satellites or moons.
The moon revolves around the Earth, hence, it is a natural satellite of the Earth.
In modern times when you talk of a satellite, you need to be cautious about which type of satellite you are talking about natural satellite or artificial satellite. The artificial satellites are the man-made satellites that are launched into space by rockets to carry out the desired functions for mankind. At present only six countries in the world have the technology for developing the artificial satellite. India has launched many satellites into space. These include INSAT, IRS and Rohini series of satellites. Aryabhatta was the first artificial satellite to be launched by India in 1975.
Artificial satellite
The artificial satellites, based on the type of orbit in which they revolve around the earth have further been classified into two types, polar and equatorial orbit satellite. The polar orbit which passes over the north and south poles of the earth, the equatorial orbit lies around the equator of the earth.
Advantage of Artificial Satellites: The use of artificial satellites has influenced the life of every individual, whether a scientist or layman, to an extent that the people have started calling the present age as space age with the tremendous improvement in the quality of life ranging from the weather forecast to the use of cellular phones. Some applications of artificial satellites include:
1. Satellite Communication: It is the communication that uses a satellite to make long-distance calls, television transmission, and radio broadcast, and sending of the telex and fax messages. This is achieved by satellites orbiting in equatorial orbit at the speed of earth's rotation and remain stationary at a point with respect to earth to receive and transmit the messages. These satellites are also called geostationary satellites.
Satellite communication
Satellite communication
Long-distance transmission of television programs or radio broadcast has become possible with the help of geostationary satellites. The picture or sound or both are converted into electrical signals with the help of a video camera. These electrical signals are then converted into a type of waves that are transmitted using transmitter antenna to an artificial satellite station in the equatorial orbit. These satellites are equipped with special instruments to receive these signals and re-transmit them after their amplification. The signals transmitted to far off places are received by antennas and dishes like the ones used by cable operators. Once received, the waves are transformed back into electrical signals to operate the television screen or radio or telephone. These devices themselves act as a converter of electrical signals into an image and sound.
Moon is the natural satellite of the earth but it cannot be used for long-distance communication because of limitation which includes its long distance from the earth and the difference in its period of revolution and rotation of the earth.
Weather monitoring
2. Weather Monitoring: It allows providing beforehand information on weather conditions of an area to the public. This information, provided by a satellite orbiting in polar orbits, helps the public prepare beforehand for a forthcoming storm or hurricane to minimize the loss of life and property.
3. Remote Sensing: It is the taking of photographs and collection of information about a place from a distance without coming in physical contact. These satellites are launched in polar orbit for groundwater survey, assessment of drought, crop yield, and survey of coal, oil or ore reserves.
Satellite taking photograph of a place: Remote sensing
Space exploration
4. Space Exploration: It is a recent step taken in the last decade or little more to explore the space to gain more knowledge and information about the members of the solar system and other celestial bodies.
Universe:All the space consisting of galaxies and other celestial bodies.
Galaxy:A group of about 100 billion stars.
Stars:They are the luminous bodies found in the universe.
Solar system:The system of eight planets revolving around the sun with other celestial bodies such as comets, asteroids, and meteors.
Planets:The non-luminous celestial bodies that revolve around the sun.
Constellation:A small group of stars positioned with respect to each other to give some definite shape.
Comet:A small celestial body with an elliptical orbit around the sun.
Meteors:The celestial bodies that happened to enter the earth's atmosphere.
Meteorites:Meteors that happened to land on the earth's surface in the form of rocks.
Asteroids:The celestial bodies like small planet that revolve around the sun between the orbits of Mars and Jupiter.
Satellites:The celestial bodies that revolve around a planet.
Artificial satellite:The man-made satellite that revolves around the earth.
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If you want to know more, this video will be definitely helpful for you. Enjoy the video!
Among all forms of living organisms existing on the earth, there are few that you can see with your naked eyes whereas there are many others that you fail to see with your naked eyes. These living organisms that you fail to see with your naked eyes are called 'micro-organisms'.
(Antonie van Leeuwenhoek)
The knowledge of their existence came after the discovery of cell by Robert Hooke in 1665 when Antonie van Leeuwenhoek observed the first living cell in a drop of pond water. The organism observed by him were bacteria. Later in 1857, Louis Pasteur with the germ theory and concept of vaccination proposed and laid the foundation of 'microbiology'.
Microbiology is the branch of science that deals with the study of micro-organisms. Louis Pasteur is known as the father of microbiology for his discovery of vaccines for rabies, anthrax and for the simple but well-known technique of 'pasteurization'.
Activity
Take a drop of pond water on a slide. Place the coverslip on the drop of pond water.
Using the higher magnification of the microscope, observe the water drop. Record your observations.
Where do micro-organisms live?
(Amoeba)
They can survive under all types of environments, ranging from ice cold climate to hot springs and deserts to marshy lands. They are also found inside the bodies of animals including humans. Some micro-organisms grow on other organisms while others exist freely. Micro-organisms like amoeba can live alone, while fungi and bacteria may live in colonies.
Types of micro-organisms
The micro-organisms, found on the earth, differ from each other like the rest of the organisms that you see in your surroundings. All these micro-organisms have been classified into five different categories. These are viruses, bacteria, algae, fungi, and protozoa.
Viruses: These cannot be seen through a simple microscope. To see viruses we need a very powerful electron microscope. These are the smallest of all micro-organisms. These consist of nucleic acid covered with the protein shell. Viruses exhibit a variety of shapes, having a simple structure. Viruses are living only inside living organisms and remained non-living outside living organisms. They can cause many diseases.
Bacteria: Bacteria are responsible for the largest number of diseases as compared to any other micro-organisms. They vary in their shapes, sizes, and habitats (dwelling places). In size they have range from 0.2 to 100 microns, with the smallest bacteria known is 0.15 micron and, the largest is 1.5 micron in diameter and 15 micron in length (1 micron = 1/1000 mm or 1ｘ10-6 metre).
Bacteria are unicellular micro-organisms. They do not have a define cellular nucleus. These are divided into four groups based on their shape: Cocci, Bacillus, Spirillum and Vibrio. Some bacteria live on their own whereas others are dependent and form colonies. These further can be classified into three groups depending on their response to gaseous oxygen: aerobic - that needs oxygen to survive, anaerobic - that can live without oxygen and anaerobes - this can live in both environments.
Algae: Algae are a group of eucaryotic oxygenic photosynthetic micro-organisms that contain chlorophyll (as seen in plants). Algae range from single-celled organisms to complex multicellular organisms like seaweeds. Algae inhabit a wide range of habitats from aquatic environments (freshwater, marine, and brackish) to soils and rocks; only inadequate light or water seems to limit the presence of algae. Algae are most commonly found in saturated environments either suspended (planktonic), attached to surfaces, or at the air-water interface (neustonic).
Fungi: The fungi may appear to be plants, but they do not have leaves, roots, and chlorophyll. These are simple non-green plants that are not photosynthetic, they are heterotrophic. Some fungi such as Puccinia, Albugo, Ustilago, etc. are parasites, drawing their nutrients from living cells of the host plants. They may be unicellular.
Activity
Visit a pond and collect some green scum floating on its surface. Wash the collected scum, and place a little of it on a glass slide. Properly spread the mesh of the scum, and observe it using a microscope.
Record your observations in the form of a labeled diagram.
Protozoa: Protozoa are unicellular (one-celled or single-celled) mostly aquatic. They are solitary or colonial, free-living for parasitic or symbiotic. Their body shape may be irregular, spherical, oval, elongated and flattened.
Useful micro-organisms
Micro-organisms are used for various purposes. All viruses, some bacteria, and some fungi are harmful but most micro-organisms are beneficial. Let us discuss some useful micro-organisms.
Useful Bacteria
1. Most bacteria are decomposers. Some decompose plant and animals remains, and release minerals into the soil and carbon dioxide into the air. Some act on nitrates in the soil and release nitrogen into the air. We use bacteria to treat sewage and to produce biogas from waste. We have also started using them as clean up oil spills.
2. Nitrogen-fixing bacteria draw nitrogen from the air and convert it into ammonia, nitrites, and
(Nitrogen-fixing bacteria
in the root of the plant)
nitrates, which enrich the soil. Some bacteria help to dissolve minerals present in the soil. Plants cannot absorb these minerals unless they are redissolved.
3. Herbivorous, like cows and goats, can digest grass because of the presence of cellulose-digesting bacteria and their stomach. Human beings also benefit from the presence of some beneficial bacteria in their intestine.
4. Certain bacteria are used to make antibiotics. Some others are used for industrial production of vinegar, ethyl alcohol, butanol, and organic acids. Bacteria are also used to make enzymes, vitamins hormone, proteins, and other useful biochemicals.
5. Certain types of bacteria are used for the tanning of leather, and the curing of tea and coffee.
6. Some bacteria are very useful to use research tools in molecular biology, biochemistry, and biotechnology. Major discoveries related to the structure and function of genes protein synthesis and immunology has been made as a result of studies on bacteria.
Useful Fungi
1. Most fungi are decomposers. They add nutrients to the soil by decomposing organic matter.
2. Penicillium, a soil fungus, is used to originally produce in 1940; penicillin was the first antibiotic to be made.
3. Yeast used for the production of wine and other alcoholic beverages, bread, idli, dosa, and many other fermentative products, is a fungus. It is also used to produce proteins and vitamins.
(Mushroom)
4. Mushroom and morels are also fungi. These are widely cultivated and eaten for their taste and nutritive value.
1. Algae not only supply food to aquatic animals but also release oxygen into the air through photosynthesis.
2. Some red algae are eaten in certain countries. Some are used as animal feeds, while others are used for making toothpaste, glue, jelly, and so on. Agar, used for chicken jelly and puddings, and in biological research is obtained from two types of red algae.
(Blue-green algae in the lake)
3. A few blue-green algae, like Nostoc and Anabaena, are very useful for agricultural as they enrich the soil with nitrogen. They are used mostly in rice fields.
4. Some brown algae are important sources of iodine and potash, while some are used to produce confections (sweets). Note:All the viruses are not useful. They are all harmful.
Harmful micro-organisms
Micro-organisms are harmful in many ways. Some of the micro-organisms cause diseases in human beings, plants, and animals. Some spoil food, clothing, and leather.
We can classify various diseases according to the type of causative organism or pathogen.
Disease
Mode of Transmission
Causative Pathogen
Preventive Measures
Malaria
Bite of the female Anopheles Mosquito
Protozoa
Not allowing mosquitoes to thrive in the locality
Cholera
Contaminated food and water
Bacterium (singular form of Bacteria)
Maintain proper sanitation practices, Boiling water before drinking
Typhoid
Contaminated food
Bacterium
Maintain proper sanitation practices
Tuberculosis
Air
Bacterium
Vaccination
Ringworm
Direct contact with the infected person
Fungus (singular form of Fungi)
Good hygiene, Not sharing personal items
Common Cold
Air
Virus
Washing hands regularly, Avoiding close contact with people having the common cold
Poliomyelitis
Air and water
Virus
Vaccination
Chicken Pox
Air, physical contact with the infected person
Virus
Vaccination
How to avoid spreading harmful micro-organisms
You can avoid spreading harmful micro-organisms by:
1. Washing your hands before eating, after preparing food, and after using the toilet.
2. Covering your mouth when you cough or sneeze.
3. Keeping away from other people if you have a disease that is easily spread.
4. Not eating food which is not fresh or has not been cooked properly.
5. Keeping uncooked meat separate from other foods in the fridge.
Food spoilage
(Food spoilage)
When you keep bread outside the refrigerator for a few days, spongy growth is seen on it, which may be white, green and black in color. The bread thus gets spoilt due to the growth of mold and becomes unfit for consumption. Likewise, if cooked dal or vegetable is left outside for some time, it develops a bad smell and bubbles due to fermentation.
The dal and vegetables are spoilt and cannot be eaten. Can you now say when is a food spoilt?
Food is said to be spoilt if there is rotting i.e. bad smell, fermentation i.e. bubbles/gas in the food or mold i.e. spongy growth on the foodstuff. The formation of the soft spot on or soft brown spots on fruits and vegetables is also food spoilage.
(Stale food)
Micro-organisms spoil food items when the condition for their growth is appropriate. What are these appropriate conditions? Like all living beings micro-organisms require air, moisture, right temperature and food to grow and multiply. The situations which provide appropriate conditions for the growth of micro-organisms can be listed as:
1. Food having high moisture content.
2. Air around the food containing micro-organisms.
3. Food kept for a long time at room temperature.
4. Skin of fruits and vegetables getting damaged, thus exposing the food to micro-organisms.
5. Food with low salt, sugar or acid content.
Methods of preserving food at home
Food can be preserved at home by the following methods:
Can you name some dried food items that are stored in your kitchen for a period of one year or more? Are these potato chips, sevia (vermicelli), methi, papad, ginger powder?
These are the foods that have been preserved by the dehydration method. The word dehydration means removing water or moisture from food. The home method of dehydration is sun drying. The most appropriate weather to dry food is when the air is dry and there is strong sunshine.
Lowering temperature
(Refrigerator)
Using low temperature to preserve food works on the principle that low temperature slows microbial and enzyme action. The food is thus prevented from spoilage. Are you using this method of preservation at home? Yes, if you have a refrigerator you can use it because a refrigerator work on this principle. Food can be preserved at low temperature by:
(a) Refrigeration -400 C to -700 C
(b) Cold storage -100 C to -400 C
(c) Freezing -1800 C or below
The duration for which the food can be preserved by using low temperature varies with the types of food and the temperatures. The lower the temperature, the longer is the duration for which food can be preserved. Of the three methods, freezing uses the lowest temperature.
Increasing temperature
By increasing the temperature, enzymes and micro-organisms are destroyed, leaving the food safe from spoilage. Do all organisms get killed by increasing temperature?
There are only two methods of preserving food by using high temperature:
(a) Pasteurization (b) Sterilization
(a) Pasteurization: When you think of pasteurization, which food item comes to your mind? Yes, it's milk. We have often heard about pasteurized milk packets.
Note:The photo in the middle is of Louis Pasteur. He discovered the principle of Pasteurization.
In this method, food is heated to a high temperature and then quickly cooled. The micro-organisms are not able to withstand the sudden change in temperature and destroyed. However, some organisms still survive in this method.
(b) Sterilization:What does the word sterilization mean?
(Sterilization)
It means free from any living organism. The high temperature used in this method to destroy all the micro-organisms in the food. The foods are exposed to a high temperature for a long time and in some cases under pressure.
When a pressure cooker is used to cook, the food lasts longer because most micro-organisms get destroyed. You can also sterilize bottles and other pieces of equipment used in preservation.
Using preservatives
What are preservatives? Any substance that is added to food to keep it for a long time is called a preservative.
You have learned that increasing the concentration of salt, sugar or acid in food prevents its spoilage. Therefore salt, sugar or acid are the substances that act as preservatives.
There are two types of preservatives:
(Natural preservatives)
(a) Natural preservatives: Salt, sugar, lemon juice, vinegar, oil, and spices are natural preservatives.
(Chemical preservatives)
(b) Chemical preservatives: Potassium metabisulphate, citric acid, and sodium benzoate are chemical preservatives.
* Useful words
Micro-organisms:The organisms that cannot be seen with naked eyes but can only be seen with the help of a microscope.
Virus:The smallest of all micro-organisms, cause disease when in contact with living organisms.
Bacteria:Unicellular organism, not having a well defined cellular structure.
Algae:Photosynthetic micro-organisms, not differentiated into roots, stem or leaves.
Fungi:Heterotrophic in nature, maybe parasitic or saprophytic.
Protozoa:Unicellular, show animal-like characteristics cause diseases in man and animals.
Pathogens:Organisms that cause disease.
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Now, Answer time!
Answer the questions given below. Tell us your answers through the comment.
1. Name the different types of micro-organisms found in the atmosphere.
