LENSES

     A lens is a portion of a transparent medium bounded by two surfaces both of which are usually spherical or one Surface spherical and the other plane. There are two types of lenses. They are

1.CONVEX LENS

A Convex lens is thick at the middle and thin at the outer region. A parallel beam of Light rays. After refraction through a convex lens converges. Therefore, this lens is called as converging lens. 

2.CONCAVE LENS

A concave lens is thin at the middle and thick at the outer region. A parallel beam of light rays after reflection through a concave lens diverges. Therefore, this lens is called as diverging lens. 

Submarines

According to Archimedes’ principle, when a body is immersed in a liquid, it suffers an apparent loss of weight equal to the weight of the liquid displaced by it.

In the submarine boats, there is an internal water tank. When cruising the free surface level of water is AB and a considerable portion of boat is above the water.(a)

         

The boat may be sunk lower in the water by admitting water into the internal tanks. Now the free surface of water AB may be much above the boat (b). Pumps are used for emptying the water tanks, thus brining the boat again to its original surface level.

Applications of Archimedes Principle

Archimedes’ principle is used to find the specific gravity  of liquids and solids. This principle is also used in the submarines. 

Archimedes's principle

A bucket fully immersed under water in a well appears to be very light. When this bucket is brought above the water level it weighs quite heavy. When the bucket is under the water level, the liquid displaced by the bucket exerts an upward force on it. This is known as the resultant up thrust    (or) buoyancy.

Archimedes’ principle states that, “when a body is immersed in a liquid it suffers an apparent loss of weight equal to the weight of the liquid displaced by it”. 

Effect Of Atmospheric Pressure

Take a tin can. Remove the lid and pour some water into it. Heat the can for a few minutes. The water vapor displaces most of the air in the can. Close the can with the lid tightly and stop heating. Cool the can under the tap water and observe what happens to the can. When cold water is poured on the can, the steam condenses into water and the pressure inside the can decrease. The atmospheric pressure outside the can is higher than the pressure inside the can and soothe tin can gets crushed. This experiment shows the existence of the atmospheric pressure.

Atmospheris Pressure

• The envelope of air surrounding the earth is called atmosphere.
• It extends up to a height of about 800km.
• The density of air decreases as height increases.
• Air surrounds the earth because of the gravitational pull of the earth on it.
• The atmospheric pressure is caused by the weight of the air.
• “Once atmospheric pressure is the weight of the air exerted over an area of one square meter”.

Variation of Pressure with Depth

Take a tall metal cylinder with a few holes on its side at various levels. Each hole has the same diameter. The holes are initially closed by corks. The cylinder is filled with water. When all the holes are opened, water rushes out through them but with varying forces. The water from the lowest hole falls for away from the cylinder.

This experiment clearly shows that the pressure of the liquid increase with depth. 

Pressure

Pressure is defined as the force acting over unit area. The unit of pressure is Newton/m^2

       (or)

Pressure is defined as the thrust acting normally on unit area, unit N/m^2 or Pascal.

HYDROSTATICS

Hydrostatics is the branch of science of fluids at rest and it is a sub field with in fluid mechanics.

Hydrostatics deals with the equilibrium of fluids. Liquids and gases can flow freely and for this reason, they are called fluids. Fluids do not have a fixed shape like solids.

Pluto

Is pluto a planet? 

http://www.universetoday.com/13573/why-pluto-is-no-longer-a-planet/

http://www.space.com/2791_pluto_demoted_longer_planet_highly_controversial_definition.html

 

Neptune

• It is very far off and can be seen only through telescopes.
• Discovered on September 23, 1846.
• Neptune has a faint and fragmented ring system.
• The temperature of the neptune is 55K(-218.c)

Uranus

• It is a third largest planet and appears green when seen through a telescope.
• Sir William Herschel announced its discovery on march 13, 1781.
• It is the coldest planetary atmosphere in the solar system with minimum temperature of 49K(-224.c).
•  It has a complicated planetary ring system in the solar system after saturn's.

Saturn

• Galileo first observed it with a telescope in 1610.
• It is seen with naked eyes as a bright yellow planet.
• Saturn has several beautiful rings around it.Consisting mostly of ice particles with a smaller rockey debris and dust.
• The division between the main and the outer rings is called "Cassini's division".

Jupiter

• Jupiter is the largest planet of our solar system.
• It is covered by clouds composed of ammoniya crystals and an enormous red spot can be seen in the clouds.
• It's upper atmosphere is composed of 88-92 % of Hydrogen and 8-12 % of Helium.

Mars

• Even for naked eyes Mars appears reddish.
• The Mars is visible from the earth for most part of the year.It is mostly reffered to as the "Red planet" because of its reddish appearence.
• Mars has relatively thin atmospher.The atmosphere on marss consists 95% of carbon-di-oxide.

Earth

 

• The earth is the only planet known to have life (geological activity) in the universe.
• Earth is the third planet from the sun and the fifth largest of the eight planets in the solarsystem.
• The earth rotates once in 24 hours about an imaginary axis that passes through its north and south poles. The day and night on the earth occur due to this rotation.Earth radius is 6371Km.
• The earth completes its journey around the sun in 365.25 days.With 29.78Km/s speed.
• The axis of rotation of the earth with respect to its orbits plane is tilted by an angle of 23.5.This tilt causes changes in seasons on the earth.It has one natural satellite is called moon. 

Venus

 

• Venus is similar to the earth in respect of radius,mass(0.815 Earth masses) and density. So,it has been rightly called the earth's twin.
• Venus is a brilliantly shining planet as it reflects as much as 85% of the sunlight falling upon it.
• Venus reaches its maximum brightness shortly before sun rise or shortly after sun set. For which reason it is often called the morning star or the evening star.
• Venus appears as an evening star just above the western horizon and it also appears in the eastern sky as morning star.
• Surface temperature of the venus is 700k,although all planetary orbits are elliptical, venus is closest to circular. 

Mercury

• The planet nearest to the sun is called Mercury.Mercury Is the smallest planet in the solar system. The surface of Mercury is full of craters of different sizes similar to that of the moon.
• Mercury has almost negligible atmosphere consists of atoms blasted off itds surface by the solar wind
• The surface temperatures range from about 90K to 700K(-183C to 427C).
• Mercury is hidden in the sun's glare most of the time
• So it is occasionally visible just before the sunrise or just after the sunset

Planets

• The solar system consists of Eight planets.They are Mercury,Venus,Earth, Mars(four inere planets).Jupiter,Saturn,Uranus,Neptune ( four outer planets).
• The motion of planets in their orbits is due to the force of gravitation of the sun on them. The planet Mercury is nearest to the sun and Neptune is farthest from the sun.
• Jupiter is the largest of all the planets and Saturn is the second largest.
• Between Mars and Jupiter there is a belt of minor planets are called asteroids. They revolve in elliptical orbits around the sun.
• Mercury and Venus are called inferior planets,as their orbits are smaller than that of the earth.The other planets are called superior planets whose orbits are larger than that of the earth.
• In the solar system,only the sun emits its own light. The planets appear bright by reflecting the light falling on them from the sun.
• In addition on the sun,Eight planets and their satellites,and asteriods,the solar system contains many bodies called comets and metetors.
• It is believed that the sun has a total life of about 10 billion years. Out of which,nearly 5 billion years is already over.
• The sun is made up of extremely hot gases giving out huge flames.Also, sun is the only source of heat and light energy to all the heavenly bodies that revolve around it.

SOLAR SYSTEM

A part of the Milkyway in which sun occupies a central position of the system holding together all planets, satellites and other heavenly bodies that revolve  around it is called solar system.    

INTRODUCTION

PHYSICS Physics is the systematic study of the way objects, matter and energy moves,changes and interacts.It is really concerned with how fasts things move, When they move and what causes things to move, those things can be the very large like stars or galaxies or the very small groups of objects or single objects it is also about what make up the fundamental building blocksof the reality we live in.

WHY IS PHYSICS IMPORTANT? 

        Studying the way things moves and interact the world is fundamentally usefull in all sorts of way. In some cases it is crucial to our survival. Interestingly our own brain have needed to develop an automatic understanding of physics for example being able to walk or balance requires our brain to make lots of calculation about friction and forces physics is crucial to virtually all of our modern technology, conveniences and infrastructure.From computers to cameras and everyday appliances

INTRODUCTION ABOUT THIS PROJECT 

 

        When we look at things in the solar system, we try to measure what we see. This allows us to compare the many objects and to know how and where will they ,will move, what they consists....etc., In this first chapter may answers the simple questions about the solar system. Our solar system is belived to be about five billions years old and formed at same time as the sun. Our solar system consist of an average star we call the sun, the planets Mercury,Venus,Earth, Mars,Jupiter,Saturn,Uranus,Neptune, satellites to the planets,comets, asteroids andmeteroids. The sun is richest source of electromagnetic energy.The first chapter gives basic information about the all planets this will enchance once knowledge whom unknown face to the solar system. 

       The total energy of solar system is mainly contributed by the sun. Energy is most important part for living things,Without energy no one can be in earth. Now a days there is a demand in energy due to rises of consumption and population so we need a perfect alternative way of energy creation.Today world's energy requirement may fullfill by nuclear energy we know one kind of energy can convert into another kind, by this sentences nuclear energy can convert into electrical, heat etc. Nuclear energy gives basic information about What is nuclear energy? How we can produce nuclear energy? Generally nuclear energy is obtained during the process of nuclear fission and fusion.This chapter also gives some basic introduction to nuclear reactor and atomic bomb.There are some causes in obtainig energy from this process but we have not alternative way to escape from this one. Also one can understand how energy in the sun is formed by this chapter simply this chapter creates a way for unknown phaces to nuclear energy. 

        The nuclear energy provides 16% of world's electricity is the essential need of this decade people. Electricty chapter gives some details about what is background of elecricity.In BC (Before Christian year) Peoples woundered about attractive behaviour of materials .but they did not know how it happens"? This chapter gives pre history of magnetism and name factor of magnetism .Electricty and magnetism have a thick relationship between them. We can generate magnetic field arround a coil, while current electricity is passing through it.This is a simple electromagnet. This chapter can teach simple thing about electrmagnets and its applications to younger brains.

       Electricity can obtain by electromagnetic force. Force can more objects (Newton's first law) and obtain energy when objects are moving under this one. It deals about force per unit area (Pressure) exerted by a fluid at rest, which branch of physics is hydrostatics. This chapter says how pressure vary with depth? and different type of pressures.This chapter explains the man of Euraeka's Principle and its application we can assure the image of object by observing reflected electromagnetic wave(Visible light) from that.We can converge or diverge the image by using lenses. The lense chapter gives fundamental fact and classification of lenses this one give details about how to rectify the eye defects by lenses? Every livining things eye made of lense it will pass the image sense to brain it is similarly to what camera is done why capturing an image. This chapter gives source basic differents between eye and camera consequently all these five chapters can give a basic view of physics.These chapters will enchance thoughts of ones who enter to the next stage of physics

ABOUT ME

A.PARRIMALAM,

M.Phil Scholar,

Department of Education,

Mother Teresa Women’s University,

Kodaikanal – 624 101 Tamil Nadu, India.

I have created a blog on Developing Blogs to Physics for class 8th of the Tamilnadu stateboard .Blog (a contraction of the term "web log") is a web site, usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order. "Blog" can also be used as a verb, meaning to maintain or add content to a blog. Many blogs provide commentary or news on a particular subject; others function as more personal online diaries. A typical blog combines text, images, and links to other blogs, Web pages, and other media related to its topic.