8. Short/Long Notes
Solar System
The solar system is the family of the sun, planets revolving around it, the satellites of the
planets and the asteroids or meteoroids and comets etc.
• There are eight planets in the solar system.
• Starting from the sun there are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and
• All the planets revolve around the sun in their orbits.
• Meteorite analysis shows that the age of solar system is about 4530 million years.
• The sun is not the largest star of the Milky Way; rather it is an average sized star.
• It is not at the centre of the galaxy but shifted towards a side.
• The diameter of the sun is 1, 392, 140 km and its mass is 2 * 1027 tonnes.
• The outermost layer of the sun is called photosphere, has an average temperature of 5570
0C.
• The photosphere rotates at a rate of 25.38 days per turn.
• At the centre of the sun hydrogen is undergoing nuclear fusion reaction which provides
energy for the heat and light so sun.
• The planets of the solar system as well as the moons get light and sometimes heat from the
sun.
• The four inner planets of the solar system are called terrestrial plants because of their rocky
nature.
• The outer planets are called gaseous planets because they don‘t have solid surface and are
composed of gases.
Planets And Their Characteristics:
1. Mercury
• Its distance from Sun is 58 million kms.
• Its revolution period is 88 days.
• Its rotation period is 58 days, 15 hours and 30 minutes.
• It has no moon.
• It is the nearest planet to the sun.
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• It is also the smallest planet of the solar system.
• It is the fastest planet.
• Its radius is 2,433 kms and diameter is 4,878 kms.
• It is covered with holes called Craters.
• It has no atmosphere.
• The temperature on mercury vary between 420 0C (7900F) in the day and -180 0C (-2900F) at
nights.
2. Venus
Apart from the moon, Venus is the brightest object in the sky. Venus can be seen with naked eye
in the morning or in the evening. Following are the main characteristics of the Venus.
• Its distance from the Sun is 108 million kms.
• Its revolution period is 224.7/225 days.
• Its rotation period is 243 days and 14 hours (longest day)
• It has no moon.
• It is the nearest neighbour of the earth in the solar system.
• It is the brightest planet.
• It is also the hottest planet.
• Its diameter is 12,102 kms.
• It is wrapped in thick clouds of CO2 gas.
• It rotates from east to west as opposite to most other planets.
3. Earth
The earth is the largest and the densest of the four terrestrial planets. It is the most wonderful
planet of the solar system. Following are the features of the Earth.
• Its distance from the Sun is 150 million kms.
• Its revolution period is 365 ¼ days.
• Its rotation period is 23 hours, 56 minutes, 40 seconds.
• It has one moon.
• It is the densest planet.
• It is also the watery and bios planet.
• Its diameter is 12756 km (7927 miles equatorial and 7900 miles polar diameter)
• It has atmosphere which contains 78% Nitrogen, and 21% Oxygen.
• Its two-thirds surface is covered with oceans.
• The earth‘s surface is rich in Oxygen, Silicon, Aluminium, Iron, Calcium, Sodium etc.
4. Mars
• Distance form sun 228 million kms.
• Revolution period 687 days.
• Rotation period 24 h, 37 min and 22 sec.
• It has two moons Phobos and Deimos.
• Its diameter is 6794 kms.
• Mars is covered with red dust.
• It has an atmosphere composed almost entirely of CO2.
• Its average temperature is -53 0C.
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5. Jupiter
• Its distance from sun is 778 million kms.
• Revolution period 12 years.
• Rotation period 9h, 50min, and 30 sec. (smallest day)
• It has 63 moons.
• It is the largest planet of the solar system.
• It has the largest number of satellites.
• Its diameter is 1, 24,800 kms.
• Its diameter is eleven times greater than the earth‘s diameter.
• It has a dense, cloudy atmosphere of hydrogen and helium.
• It has a rock-iron-ice core about 15, 000 km (9,000 miles) thick.
• Jupiter radiates 67% more heat than it receives from the sun. this is mainly due to dissipation of
the primordial heat of the planet.
6. Saturn
In 1610, Galileo became the first person to look at Saturn through telescope.
• Distance from Sun 1427 million kms.
• Revolution period 30 years.
• Rotation period 10h, 14 mins.
• It has 62 moons.
• The largest moon of Saturn is the Titan and it is the second-largest moon in the solar system.
Titan is larger than the planet Mercury.
• It is the second largest planet.
• It has a magnificent system of rings.
• Its diameter is 1, 20, 000 km.
7. Uranus
When sky is very dark and very clear Uranus can be seen with the naked eyes. The planet was
discovered by William Herschel in March 1787.
• Its distance from Sun is 2869.9 million kms.
• Revolution period is 84 years.
• Rotation period is 16h, and 10 mins.
• It has 27 moons.
• Titania is the largest moon of Uranus.
• It has an atmosphere which is dominated by hydrogen and helium.
• Its diameter is 52, 400 km.
8. Neptune
• Distance from Sun 4496, 6 million kms.
• Revolution period 165 years (largest year)
• Rotation period 18 hours.
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• Neptune has 13 moons that we know of. The largest moon is Triton.
• It is the coldest planet.
• It is the slowest to move around the sun.
• Its diameter is 49,100 kms.
• It is known as the twin of Uranus due to their similarity of size, mass and composition.
Short Note (Solar System)
Lunar Eclipse:
The partial or complete obscuration of light of moon for an observer on the earth is called lunar
eclipse.
Lunar eclipse takes place when the earth comes in position between the sun and the moon. In this
way, the shadow of the earth is cast on the moon and the moon does not get sunlight in this
position.
Lunar eclipse occurs only when there is full moon. But this does not happen on every full moon
because of inclination of the axis of earth to its orbit.
Solar Eclipse:
Solar eclipse occurs when the moon comes in between the Sun and the earth and its shadow is
cast across the face of the earth.
The solar eclipse occurs when the moon moves to a position between the Sun and the Earth.
During this process it throws shadow on the earth. This shadow is categorized in umbral and
penumbra. The people who are in the umbral region are unable to see the sun at all. This
condition is known as the total eclipse of the sun. While the people in penumbra region can see
the sun partly this is known as the partial eclipse of the sun.
This happens with the new moon when the moon is in conjunction with the sun. this does not
happen at every new moon because of the inclination of the orbit of the moon to the orbit of earth
around the sun.
Asteroids:
Asteroids are also known as planetoids. These are small, irregularly shaped rocky objects which
orbit the Sun between the orbits of Mars and Jupiter. Asteroids are also known as the minor
planets.
Basically the word Asteroid means ―Starlike‖. Ceres asteroid was the first to be discovered.
Meteorites:
Meteorites are small chunks of iron and rock thought to be resulted from collisions between
asteroids. They also may be formed when comets disintegrate into fragments. Meteorites enter the
earth‘s atmosphere and become a meteor. A meteor is a ―falling star‖ that is usually seen in the
sky at night. A meteor will burn up from frictional heating as it enters the atmosphere. Most of
the meteors burn up before they reach the earth. If they do not reach the ground they become
meteorites. Meteorites can be seen at a distance of 70 miles from the earth. Meteorites are heavy
objects which weigh about 60 tons.
Comets:
Comets are those bodies which revolve round the sun. they are mainly composed of ice and dust.
Most comets have three parts which are as under.
i) A solid centre.
ii) A head or round coma, that surrounds the centre and consists of dust particles mixed with
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frozen water, frozen methane and frozen water, frozen methane and frozen ammonia.
iii) A long tail of dust and gases that escape from the head. Most comets stay near the solar
system.
Other characteristics of comets are as under:
• Comet is usually about 10 km or 6 miles across.
• Comets are usually made up of ice and dust.
• Millions of comets are present in the solar system.
• Halley‘s comet is the famous example.
• Comets usually move around the sun in the elliptical orbits.
Light Year:
The distance travelled by light at speed of 186,000 miles per seconds in one year is known as a
light year. One light year is approximately 9461,000 million kilometres or 5875000 miles. Light
year is also used to measure the distance between the galaxies.
Astronomical Unit:
The distance between the Sun and the Earth is called as Astronomical Unit. This unit is also used
in the measurement of distances between the heavenly bodies within the solar system. The earth
is one A.U away from the Sun and the Pluto is 39 A.U away from the Earth.
Black hole:
Black Hole is a hypothetical region in space which has a big gravitational pull for which no
matter or radiation can escape from it. Even it is believed that light cannot escape from it. Black
Hole usually likes at the centre of galaxy.
Super Nova:
A Super Nova is an exploding star. At the end of its phase as a Red Giant, a heavy star explodes
as a Supernova shining briefly as brightly as a thousand million stars. Recent Supernova was
observed on the night of Feb 23, 1987. This occurred in Large Magellanic Cloud.
Nebula:
Nebula is derived from a Greek word which means ―Cloud‖. In the sky there are clouds like
objects, which are classified as Nebulae. There are both luminous diffuse nebulae and dark
obscuring nebulae over the Milky Way. They are made up of dust and gases.
Polar Regions with a tremulous motion and giving forth streams of eightAurora . It is generally
believed that the aurora is actually caused by radiation from the Sun-spots.
Solar Wind:
Solar wind is the stream of electrically charged particles especially protons and electrons, which
are emitted by the Sun, predominantly during solar flares and sunspots activity. Some of these
particles become trapped in the Earth‘s magnetic field forming the outer Van Allen radiation belt,
but some penetrate into the upper atmosphere where they congregate in narrow zones in the
region of the Earth‘s magnetic poles producing aurora displays.
Cosmic Rays:
Cosmic Rays are charged particles moving as fast as the speed of light. Most of the particles are
protons, while some are alpha particles and electrons. They travel throughout our galaxy,
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including the solar system and some strike the earth‘s atmosphere. They can be detected by
instruments on the Earth. Nobody knows how cosmic rays are formed. Some of them are formed
by exploding stars or supernova and some come from outside our Galaxy.
Some Important Definitions:
Cosmology:
Cosmology is the science of the cosmos or universe.
OR
Cosmology is the branch of physical science which deals with the Universe.
Universe:
The universe is the sum total of all that exists, or has existed, both in space and time.
Galaxy:
A galaxy is a system of many thousands of millions of stars together with inter-stellar gas and
dust.
OR
Galaxy is a fundamental unit of the universe. It is composed of hundreds of thousands of stars
together with intra-stellar gas and dust.
Star:
Those heavenly bodies which are luminous and produce their own energy by nuclear reactions
are called stars.
• Proximal Centauri second nearest after Sun to the Earth.
• Antares is one of the largest stars known.
Solar system:
A tiny system of our galaxy which consists of the /sun, a planet and their satellites, thousands of
miniature planets called asteroids, meteoroids, comets, interplanetary dust and plasma.
Satellite:
Those heavenly bodies which revolve round the planets are called satellites.
Eclipse:
In astronomy, the term eclipse simply means the obscuring of one heavenly body by another,
particularly that of the sun or a planetary satellite.
Lunar Eclipse:
A condition when the earth comes in between the sun and the moon and throws its shadow on the
moon is called lunar eclipse.
Solar Eclipse:
A condition when the moon comes in between the sun and the moon and throws its shadow on
the moon is called Solar Eclipse.
Astrology:
Astrology is the interpretation of the influence of planets and stars on human lives.
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Asteroids:
Small, irregular shaped rocky objects which orbit the sun between the orbits of Mars and Jupiter
are called Asteroids.
Meteorites:
Tiny chunk of material floating in space which can also enter the earth‘s atmosphere and become
meteor are known as meteorites.
Comets:
The bodies mainly composed of ice and dust which revolve round the sun are called comets.
Balanced Diet:
• ―The food which contains all essential food nutrients which are necessary and essential for
healthy growth of the body and proper functioning of the whole parts of body.‖
• Food is a complex mixture of chemical substances.
• It performs following useful functions when eaten and absorbed by the body.
i) Produces energy
ii) Promote growth
iii) Repair the tissues
iv) Regulate various processes
• Nutrients are the chemical components of food capable of performing above functions.
• Example: milk is a balanced diet although it does not contain iron.
• Following are the major components of Balanced Diet and their source and functions:
i) Carbohydrates
• Source: Honey, Sugarcane, Wheat, Maize, Potatoes.
• Functions: Provide energy
ii) Fats:
• Source: Butter, Cheese, Soya bean, Mustard etc.
• Functions: Provide Energy
iii) Proteins:
• Source: Meat, Eggs, Fish, Milk, Pulses etc.
• Functions: Essential for growth
iv) Vitamins:
• Source: Fruits and Vegetables.
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• Functions: Important for proper physiologic and metabolic functions of the body.
Types:
a) Water Soluble Vitamins: B1, B2, B6, B12, C
b) Fat Soluble vitamins: A, D, E, K
v) Minerals: Minerals are those inorganic substances which play a key role in the maintenance
and building of the body tissues. The most important minerals of balanced diet are as under:
• Phosphorus: is necessary for bones and teeth.
• Iron: is an essential component of blood.
• Iodine: is necessary for thyroxin which is secreted from thyroid gland.
• Calcium: is necessary for bone development.
vi) Water:
• Source: Fruits, Vegetables
• Functions: It is constituent of blood, lymph, hormones and other secretions of the body.
Functions Of Vitamins:
1. Vitamin A
i) Role: Vitamin A plays an important role in growth and body repair, keeps the skin smooth and
essential for vision.
ii) Deficiency: it deficiency causes ―Night Blindness‖.
iii) Source: Fortified milk, butter, eggs, cream, leafy vegetables, carrot.
2. Vitamin B1
i) Role: it is an energy building vitamin, help in the digestion of carbohydrates, keep the heart
and muscle stable and necessary for nerves.
ii) Deficiency: its deficiency causes Beri Beri, muscular weakness, cramps and heart swelling.
iii) Source: Pork, cereals, legumes, nuts and seeds.
3. Vitamin B2 (Riboflavin)
i) Role: It is important in forming RBCs, protection of mouth and mucous membrane and skin.
ii) Deficiency: its deficiency causes ―Pellagra‖
iii) Source: Milk, leafy green vegetables, cereals etc.
4. Vitamin B3 (Niacin)
i) Role: Helps in releasing energy from carbohydrates, fats and proteins, very essential for the
DNA synthesis, used to lower elevated LDL cholesterol and triglyceride levels in the blood,
boosts the level of HDL, the 'good' cholesterol, in the body, essential for the proper digestion of
the food etc.
ii) Deficiency: its deficiency causes Loss of appetite, Indigestion, Skin lesions, Mental imbalance
etc.
iii) Source: Meat, poultry, fish, cereals, vegetables, peanuts, butter etc.
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5. Vitamin B6 (Pyridoxine)
i) Role: it is essential for the production of antibodies, for the CNS and help in protein
metabolism in the body.
ii) Deficiency: Skin problems, Nervous system disorders, Muscle spasms, Sleeplessness.
iii) Source: Meat, fish, poultry, vegetables, fruits etc.
6. Vitamin B12 (Cynocobalamin)
i) Role: it is important for carbohydrate and fat metabolism, growth of child and formation of
blood.
ii) Deficiency: its deficiency causes ―anaemia‖
iii) Source: Meat, poultry, fish, seafood, eggs, milk.
7. Vitamin C (Ascorbic Acid)
i) Role: It is essential for protection of bones and for healthy teeth and gums.
ii) Deficiency: its deficiency causes ―Scurvy‖
iii) Source: Citrus fruit, guava, pineapple, tomatoes, spinach, turnips, strawberry.
8. Vitamin D:
i) Role: It is very important for the growth of children.
ii) Deficiency: Its deficiency causes ―Rickets‖ in children and Osteoporosis in adults.
iii) Source: Egg yolk, liver, fish, milk.
9. Vitamin E:
i) Role: it plays an important role in wound healing, prevention of sterility, breaking blood clots
and prevents damage of cells due to aging.
ii) Source: Leafy green vegetables, soya bean, cotton seed, liver, egg yolk, nuts etc.
iii) Deficiency: its deficiency slows down the formation of RBCs.
10. Vitamin K:
i) Role: essential for blood clotting.
ii) Deficiency: its deficiency causes ―Blood clotting Disorder‖
iii) Source: Leafy green vegetables, milk, fish, liver, alfalfa.
Minerals: Their Functions, Source and Sings Of Deficiency:
1. Calcium:
i) Role:
a) It is essential constituent of bones and teeth.
b) It is vital for metabolic process such as nerve function, muscle contraction, and blood clotting.
ii) Source: Dairy Products
iii) Deficiency: Osteomalacia (softening of bones), Osteoporosis, Rickets, Tetany
2. Iron:
i) Role: It is the key constituent of haemoglobin which helps in transfer of oxygen.
ii) Source: Eggs, Green Vegetables, Fortified foods, Cereals, White flour, Liver, Meat, Nuts,
Peas.
iii) Deficiency: Anaemia, Increased susceptibility to infection.
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3. Magnesium:
i) Role: it is essential for healthy bones; muscles and nervous tissues. It is needed for functioning
of approx. 90 enzymes.
ii) Source: Eggs, leafy vegetables, fish, milk and dairy products.
iii) Deficiency: Anxiety, fatigue, insomnia, muscle problem, nausea, premenstrual problem.
4. Phosphorus:
i) Role: it is important for healthy bone tissues.
ii) Source: Dairy products, fruits, meat, pulses, leafy vegetables.
iii) Deficiency: Anaemia, demineralization of bones, nerve disorder, respirator problem,
weakness, weight loss.
5. Potassium:
i) Role: it is essential for intracellular fluid, maintenance of electrical potential of the nervous
system and functioning of muscle and nerve tissues.
ii) Source: Cereals, coffee, fresh fruits, meat, vegetables, whole-grains, flour.
iii) Deficiency: General muscle paralysis and metabolic disorder.
6. Sodium:
i) Role: it is necessary for the control of the volume of extra cellular fluid in the body
maintenance of pH of the body, and electrical potentials of the nervous system.
ii) Source: Bakery products, Table salts
iii) Deficiency: Low blood pressure, general muscle weakness, respiratory problems.
Computer:
“The word Computer is derived from compute which means to calculate. In simple and
technical term it is an automatic electronic calculating machine that processes or
manipulates a given data according to a program or set of instructions and gives a desired
output.”
Parts Of A Computer:
The computer is composed of two parts:
1) Hardware
2) Software
1) Hardware:
All physical components of computer, which can be touched, measured, have weight and occupy
space, are collectively called computer hardware viz;
i) Keyboard
ii) Mouse
iii) Joy stick
iv) Scanners
v) Monitor
vi) Printer
vii) Central Processing unit etc.
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2) Software:
Software can be defined as a set of instructions or codes written in a defined manner. In other
words softwares are prewritten programs, which control the operations of computer.
OR
All programs and data stored on floppy disk, Hard disk, CD-ROM are collectively called
softwares. Examples are;
i) DOS
ii) Window
iii) UNIX
iv) XENIX
v) Linus
vi) Java
vii) MS Office
Devices OR Components Of A Computer:
The computer is a combination of many parts, each of which performs specific task
independently. The major devices of a computer are as under.
1) Input Devices
The input devices are those devices which send data or information to the Central Processing
Unit. The main input devices are:
i) KEYBORD: It is used to enter text. It contains alphabetic, numeric and other keys for entering
data.
ii) MOUSE:It is a pointing device. It controls the pointer on the screen.
iii) MICROPHON: It is used to enter voice into the computer.
iv) SCANNER: It reads printed text and graphics and then translates the result into digital form.
v) DIGITAL CAMERA:It is used to take photos.
vi) PC CAMERA: It is used to create movie and to take photos on the computer.
2) OUT PUT DEVICES:
A hardware component used to display information to the user output device.
i) MONITER: It is used to display text, graphics and video output.
ii) PRINTER: It is used to display printed output on paper.
iii) SPEAKER:It is used to hear sound to hear sound music and voice outputs.
3) STORAGE DEVICE:
The hardware components used to store data, instructions and information permanently are called
storage devices. For example floppy disk drive, zip drive, hard disk drive, CD-ROM drives etc.
4) COMMUNICATION DEVICES:
It is used to communicate and exchange data, instructions and information with other computers.
For example Modem.
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UNITS OF CPU:
• ALU(ARTHMETIC AND LOGICAL UNIT)
ALU is a part of CPU. Actual execution of instructions takes place in this part. All arithmetic and
logical operations are performed in ALU. It consists of two units:
1. Arithmetic Unit
It performs basic arithmetic functions such as addition, subtraction, division.
2. Logical Unit
It performs logical operations like comparing two data items to find which data item is greater
than, equal to, or less than the other.
• CONTROL UNIT
It acts like a supervisor of the computer. It does not execute program instruction by itself. It
controls and coordinates all activities of computer system.
• Memory Unit (MU)
It is responsible for storage of data and information. The memory unit consists of two types of
memory which are RAM and ROM.
Some Important Definitions And Short Notes:
RAM:
RAM stands for random access memory. It is that part of CPU where temporary information is
stored.
Byte:
A group of 8 bits is called a byte.
Icons:
Pictorial objects on the desktop or screen are called Icons.
Mouse:
It is an input device, normally called a ―Pointing device‖. This device is used for pointing
anything on monitor through a blinking cursor.
Software:
A set of instructions or codes written in a defined manner or prewritten programs which control
the operations of computer.
Control Unit:
A unit of CPU which is responsible for all automatic operations carried out by the digital
computers is called CU. The CU directs and coordinates all activities of a computer.
LAN:
LAN stands for local area network. It is privately owned communication network that serves
users within a confirmed geographical area. The range is usually within a mile-perhaps one
office, one building or a group of buildings.
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WAN:
It stands for wide area network. It is a communication network that covers a wide geographical
area. The range is usually a state or a country. Examples are Telenet, Uninet etc.
Modem:
Modem is abbreviation of Modulate-de-Modulate. Modulation is a process that converts digital
signals into Analog form and Demodulation is a process that converts Analog signals into digital
form. The device which performs modulation and demodulation is called a MODEM. In simple
words it is a device that converts the digital signals into Analog and then back from Analog to
digital form.
ALU:
A unit of CPU that performs arithmetic and logical operations is called ALU.
Register:
Registers are high-speed staging areas that temporarily store data during processing and provide
working areas for computation.
Registers are contained in control unit and arithmetic Logic Unit. Following are the major types
of registers:
i) Address Register
ii) Instructions Register
iii) Storage Register
iv) Accumulator Register
Soft Copy:
It displays the data on screen of monitor. It can be carried in a floppy disk. A change can be made
in a soft copy.
Hard Copy:
The data is printed on paper card etc. with the help of printer. It cannot be carried in a floppy
disk. No change can be made in hard copy.
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