Explanation of Photoelectric Effect and their Laws.

 Explanation for the Photoelectric Effect :

The experimentally observed facts of photoelectric effect can be explained the help of Einstein's photoelectric equation.

i) Each incident photon liberates one electron, then the increase of intensity of the light (the number of photons per unit area per unit time) increases the number of electrons emitted thereby increasing the photocurrent, The same has been experimentally observed.

ii) From K(max)=h v—Φ•, it is evident max that K is proportional to the frequency max of the incident light and is independent of intensity of the light.

iii) There must be minimum energy (equal to the work function of the metal) for incident photons to liberate electrons from the metal surface. ( h v= h v 1/2 mv^2 ). 

Below this value of energy, emission of electrons is not possible. Correspondingly, there exists minimum frequency called threshold frequency below which there is no photoelectric emission.

iv) According to quantum concept, the transfer of photon energy to the electrons is instantaneous so that there is no time lag between incidence of photons and ejection of electrons. Thus, the photoelectric effect is explained on the basis of quantum concept of light.

Laws of Photoelectric Effect :

i) For a given metallic surface, the emission of photoelectrons takes place only if the frequency of incident light is greater than a certain minimum frequency called the threshold frequency.

ii) For a given frequency of incident light above threshold value, the number of photoelectrons emitted is directly proportional to the intensity of the incident light. The saturation current is also directly proportional to the intensity of incident light. 

iii) Maximum kinetic energy of the photo electrons is independent of intensity of the incident light.

iv) Maximum kinetic energy of the photo electrons from a given metal is directly proportional to the frequency of incident light.

v) There is no time lag between incidence of light and ejection of photoelectrons. 

" When you change the way you look at things, the things you look at change. "

--- Max Planck.---  

The History Of Australia 🇦🇺 (From Land to Sea)

 The History Of Australia 🇦🇺 :

🦘 Australia became inhabitant over 40,000 years ago by the Indigenous Australians or Aborigines, who are believed to have come to Australia by land bridges and short sea crossing from Southeast Asia. These people were hunters and gathers. During that time, oral history was passed down through the generations in the form of tales, myths, and songs. Over the centuries that followed, multiple colloquial language, culture and lifestyle survived in different regions of the continent.

 Map of The Commonwealth of Australia.

🦘 In the 17th Century, the European explorers began to frequent the west and north coast of Australia.

willam Janszoon (Dutch Explorer).

William Janszoon, a Dutch navigator sighted the Cape York Peninsula in 1606, but made no attempt at settling there. In the mid 18th century. The British had an overcrowded prison population and required a new penal colony. 

James Cook (British Explorer).

In 1770, Captain James Cook sailed along the east coast of Australia and claimed it for Britain, naming it New South Wales.

The First Fleet By  Captain James Cook.

 

In 1788, the first fleet arrived carrying 750 convicts. This was the first penal colony that is now the Sydney.

The Second Fleet Struggle in Port Arthur.

🦘 The second penal colony was called Port Arthur, which is a tourist attraction now. The number of colonies grew over the following decades. Australia grew into a productive farming land and a major wool producer. The mid 19th century witnessed a gold rush in Victoria and New South Wales.

James Cook Landed on Australia 🇦🇺.

🦘 In January 1st 1901, the six colonies were federated to form one nation, and the commonwealth of Australia was born. The new constitution aimed at creating a new social, cultural,and economical atmosphere, leaving the pitfalls of the old times behind. Over the following decades, Australia continued to expand and after World War II, there was a mass immigration from Europe. At one point in time, Melbourne became the largest Greek populated city outside of the Athens. the immigration has come from Asian neighbours.

🦘 Now, Australia is flourishing in terms of its national media and international business reputation. Both as a nation and as a continent.

🦘 And Australia is a continent and a country. It is known as the land down under because it is below the Equator...

   

" Don't worry about the world ending today. It's already tomorrow in Australia "   

          — Charles M. Schulz.   

 

The Story of Sumerian's Civilization

 The Sumerian Civilization emerged upon the flood plain of the lower reaches of the Tigris and Euphrates Rivers about 4000 BC. The social structure of the Sumerians was decidedly different from other societies of that and later times. 

Sumerian Civilization Map.

The Sumerian Architect.

The Sumerian communities were city states organised around a temple and ruled by a priesthood.. The temple grounds were separated from the rest of the city.

Irrigation system of Sumerians.

The cities of Sumer were the first to practice intensive, year - round agriculture. They developed core agricultural techniques including large - scale intensive cultivation of land, mono-cropping, organised irrigation, and the use of a specialised labour force.

The Cuniform Language 

The Old Buildings of Sumerian Civilization.

In addition to the priests and peasants, there was a class of craftsmen, who devoted most of their time to producing things for either the temples or the warrior-soldiers who protected the temple community. With wars of défense, the role of the warriors was manifested in the rule of kings. 

Some Inventions of Sumerians (  Sun Clock ). 

The Sumerians made the world's first boats, using the canal system, for easy waterborne transportation of people, goods, and cattle...

The Godess of Sumerians.

 " Sumer Had devised the system of structural violence that would prevail in every single agrarian state until the modern period, when agriculture ceased to be economic basis of civilization. ". 

                                            —Karen Armstrong.   

Rise of The Roman Empire

👑 The Roman Empire, located along the Mediterranean Sea, was one of the largest and most enduring in world history. It grew out of a small agricultural community founded on the Italian Peninsula as early as the 10th century BC.

        Ancient Roman Empire Map.

👑 Rome was a hub of technology, literature, culture and architecture. The Romans built strong arched bridges, and mastered the concept of "running water" using aqueducts that, among other other things, supplied public baths. 

               Romans Aqueducts. 

👑 The saying "All Road Lead to Rome" originated from the fact that the enginners of the Roman age created an unparalleled network of roads, spread over approximately 50,000 miles (80,000 km).

              Ancient Rome Roads. 

👑  Ancient Rome contributed greatly to the development of war, law, language, religion and art in the western world.

       Ancient Romans Architecture.

👑  Theatre was very important in the lives of the Romans. It was another way of keeping people busy and happy, so they would not plot against the emperor.  

          Ancient Roman period Theatre.

👑 Julius Caesar:

                             🔱 Julius Caesar (100 BC - 44 BC) was a Roman statesman, general and notable author of a Latin Prose. He played a critical role in the events that led to the demise of the Roman Republic and the rise of the Roman Empire.

                      Julius Caesar.

                            🔱 Caesar's Victories in the Gallic Wars, completed by 51 BC, extended Rome's territory to the English Channel and Rhine. Julius Caesar introduced the Julian calendar and Julius face was depicted on Roman coins...  

   Julian Calendar and Julius faced coins. 

" I Came, I Saw, I Conquered. "

                          — Julius Caesar.   

The Protestant Reformation

As the Renaissance spread throughout Europe, the standard of living improved and more people could afford to recieve a formal education. These educated people felt that the practices and teachings of the Church were not consistent with the teachings found in the scriptures. So, they began to criticize the Catholic Church. The movement that followed is termed as  “ the Protestant Reformation ”. 

       Reformation in Germany by Luther.

The Protestant Reformation was led by Martin Luther, a monk from Germany.

                        Martin Luther. 

 He collected a list of 95 different points of doctrine where he felt that the Church was incorrect and nailed the list to the door of the Catholic Church in Wittenberg,  Germany, on October 31, 1517.

       Martin Luther at the Diet of Worms.

The movement resulted in the Catholic Church loosing out on the money that they collected in exchange for indulgences.

           King Henry VIII of England.

 King Henry VIII supported the ideas of Luther, and laid the foundations of Protestantism in England, which would later transform England from a Catholic to a Protestant nation.

     Fight between Islam and Protestants.

By 1603, the Protestant Reformation in this country was complete. And Martin Luther founded a new religion known as Lutheranism...  

“ The Law Says, “ Do This ”, And It Is Never Done. Grace Says, “ Believe In This ”, And Everything Is Already Done.”

                        — Martin Luther.   

Motor Car

Daimler, Maybach and Benz introduce the first practical gasoline-engine automobile.

It is difficult, if not impossible, to imagine a world without the motorcar. When German engineer Karl Benz ( 1844-1929 ) drove a motorcar tricycle in 1885 and

                          Karl Benz 

 fellow Germans Gottlieb Daimler (1834-1900) and

                    Gottlieb Daimler

 Wilhelm Maybach (1846-1929) converted a horse-drawn carrige into a four-wheeled motorcar in August 1886, 

                     Wilhelm Maybach

none of them could have foreseen the effects of their new invention.

Benz recognized the great potential of petrol as a fuel. His three-wheeled car had a top speed of just ten miles (16 km) per hour with its four-stroke, one cylinder engine. After receiving his patent in January 1886, he began selling the Benz Velo, but the public doubted it's reliability. 

The Patent Document awarded to Karl Benz in 1886.

Benz's wife Bertha had a brilliant idea to advertise the new car. In 1888 she took it on a 60-mile (100 km) trip from Mannheim to near Stuttgart. Despite having to push the car up hills, the success of the journey proved to a skeptical public that this was a reliable mode of transport.

            First motor car by Benz & Co.

Daimler and Maybach did not produce commercially feasible cars until 1889. Initially the German inventions did not meet with much demand, and it was French companies like Panhard et Levassor that redesigned and popularized the automobile.

          Panhard et Levassor Car (French).

 In 1926 Benz's company merged to form the Daimler-Benz company. Benz had left his company in 1906 and, remarkably, he and Daimler never met. Due to higher incomes and cheaper, mass-produced cars, the United States led in terms of motorization for much of the twentieth century.

           Daimler Benz Car Company.

This kind of movement has, however, come at a cost. Some 25 million people are estimated to have died in car accidents worldwide during the twentieth century. Climate-changing exhaust gases and suburban sprawl are but two more of the consequences of a heavy reliance on the automobile...

" If I had asked people what they wanted, they would have said faster horses."

                                — Henry Ford.  

The Greek Civilization

The earliest Greek civilization thrived nearly 4,000 years ago. The Ancient Greeks lived in Greece and the countries that we now call Bulgaria and Turkey. The Greek Empire was most powerful between 2000 BC and 146 BC.

                    Ancient Greek Map

Ancient Greece was split into many different states: each state had its own laws, government and money but they shared the same language and religion. The two most important city states were states were Athens and Sparta.

           Right side - Athens ; Left side - Sparta.

The Greeks focused more on the mind instead of the gods.

.              Greek Philosopher - Sócrates 

They developed new ideas for government, science, philosophy, religion, and art. Their influence is still felt by us today. 

                           Greek Sculptures 

The word “ democracy ” is Greek; it means “ government by the people ”. The word ‘ theatre ’ is Greek; most modern theatres follow the Greek plan.“ Polis ”, the Greek word for “ city state ” is where the word “ Politics ” came from. The first Olympic Games were held in 776 BC at the Greek city of Olympia.

.                First Olympic games ( 776 BC )

Throughout the world, buildings have been constructed in the style of Ancient Greece

                 Greek mythology Gods Painting 

The Ancient Greeks played an important part in the development of the alphabet. The first two letters of the Greek alphabet - alpha and beta - have given us the word “ alphabet ”... 

“ The Ancient Oracle Said That, I Was The Wisest Of All The Greeks. It Is Because I Alone, Of All The Greeks, Know That I Know Nothing. ” 

                                                              — Sócrates. 

The Egyptian Civilization

Ancient Egypt was an ancient civilization of eastern North Africa and it developed around the river Nile. Egypt was an agricultural state. The Egyptian turned desert patches into farmlands, irritating them with the Nile's water. The yearly flooding of the Nile enriched the soil and brought good harvests and wealth to the land. The people of ancient Egypt built mudbrick homes in villages and in country.

              Egyptian Civilization Map

The main Egyptian god was Amon Re, the king of all gods. One important Egyptian symbol was that of the solar disk surrounded by the sacred snake. Crocodiles were sacred in the ancient Egypt, and they were even embalmed. Ibis was the sacred bird.

                            Amon Re

Egyptians used hiéroglyphic inscriptions - a writing system using picture symbols or diagrams. These diagrams were thought to have magical powers.

             Hieroglyphic Inscriptions

 To preserve the magical power of their art. the Egyptians believed they must copy exactly the style handed down through the ages. This meant that most artists painted in the same way, and the people they painted all looked the same.

The Egyptians loved music and played instruments like the harp. They loved beauty and fashion; eye paint was worn both by men and women. They also used a lot of perfume and jewellery .

The Egyptian people believed that their rulers, or pharaohs, were gods, and that they would continue to work even after their death. So, they preserved the bodies of the kings through the process of mummification. Mummies were entombed and included food, gifts and provisions were kept there for the afterlife.

                 The Pyramid Of Giza 

The pyramids were built to contain the tombs of pharaohs To avoid the theft of the treasures and tomb's profanation, the architects built a real labyrinth of false passages inside the pyramid, to confuse the thieves. The pyramids were the earliest buildings ever to be made by precisely cutting and putting together great blocks of stone. One of the most famous pyramids is the Great Pyramid of Khufu. It has 2,300,000 blocks and each block in the pyramid weighs 2.5tons.

                      Mummification 

The civilization coalesced around 3150 BC and lasted for three millennia until the conquest of Alexander the Great...  

 “ From The Heights Of These Pyramids, Forty Centuries Look Down Upon Us. ”

                                   — Napoleon Bonaparte.

What is Space?

Space holds many secrets. It contains places  where human beings can be stretched into spaghetti shapes, or boiled, or frozen solid: that's  why astronauts wear protective clothing in the  space. 

Welcome to a mysterious — and endlessly fascinating — world. 

♦ What is space?

                               When people think of space,  they think of:

                      ♠ Weightlessness — everything  floats as if there's no gravity.

                       ♠ Nothingness — vast areas of  space are completely empty.

                        ♠ Stars —  every star is a burning ball of gas. Our Sun is a star.

                         ♠  Astronauts — people who  explore the world beyond our Earth.

                          ♠ Rockets and Satellites — These  are what scientists use to explore space.

                           ♠ Silence — there is no air in  space, so there is absolutely no sound.

 

♦ Is that space?

                              On a cloudless night, you can see  thousands of stars. Space is the name we give to  the huge empty areas in between the  atmospheres of stars and planets. Apart from the odd rock, space is sprinkled only with dust and  gas.

♦ Why is space so dark?

                                            Space is black because  there is nothing there to reflect light. From space,  Earth looks lit up because light from our Sun  reflects off sea, and land, and the particles in our  atmosphere.

♦ How the distance is measure in space?

                                                                         The  distance measure in space in light years. One light year is the distance light travels in one year: that's  10 million million km ( 6 million million miles ). 

♦ Is anyone there?

                                  • If there are aliens, it is unlikely they will speak the languages of Earth, so  communication may be a problem. Coded signals  have been sent into space. People are also  listening for signals from space.

           

                                   • SETI ( The search for Extra Terrestrial Intelligence ) uses powerful radio  telescopes to scan for alien signals. However, so  far nothing has been found. 

         

                                   • Message into space:

                                                                         In 1974,

 astronomers at Arecibo, Puerto Rico, sent a radio  message from us to the stars. It was sent towards 

a cluster of stars called M13, where it will arrive  in 25,000 years. We may then get a reply after  another 25,000 years.( Is anyone there to read it ! )

                                    

 The Arecibo message lasts  three minutes. It is consists of 1,679 pulses,  which when arranged from a pictogram. The  pictogram explains the basis of life.

♦ Is a black hole may be a doorway to another  universe?

                 Some people think a black hole may be a doorway to another universe. But it's all just  speculation. Nobody really knows. However, it is  doubtful someone could survive the journey  through the hole to find out. An astronaut unfortunate enough to try would be stretched out  like a piece of spaghetti... 

            

              ♥ “ Two Possibilities Exist: Either We Are  Alone In The Universe Or We Are Not. Both Are Equally Terrifying. ”

                                — Arthur C. Clark.