Introduction The
Quantum Theory was the second of two theories which drastically changed the way we look at our physical world today, the first being Einstein’s
Theory of Relativity. Although both theories revolutionized the world of physics, the Quantum
Theory required a period of over three decades to develop, while the Special Theory of Relativity was created in a single year. The development of the Quantum Theory began in 1887 when a
German physicist, Heinrich Hertz, was testing
Maxwell’s Theory of Electromagnetic Waves.
Hertz discovered that ultraviolet light discharged certain electrically charged metallic plates, a phenomenon that could not be explained by
Maxwell’s Wave Theory. In order to explain this phenomenon termed the photoelectric effect, because both light and electricity are involved, the
Quantum Theory was developed. The
Photoelectric Effect Maxwell’s work with the
Theory of Electromagnetic Waves may seem to have solved the problem concerning the nature of light, but at least one major problem remained.
There was one experiment conducted by Hertz, the photoelectric effect, which could not be explained by considering light to be a wave. Hertz observed that when certain metals are illuminated by light or other electromagnetic radiation, they lose electrons. Suppose we set up an electric circuit. In this circuit the negative terminal of a battery has been connected to a piece of sodium metal. The positive terminal of the battery is connected through a meter that measures electric current, and to another piece of metal. Both of these metal plates are enclosed in a sealed glass tube in which there is a vacuum. When there is no light illuminating the sodium plate, no current will flow, and therefore there is no reading on the meter. A reading on the meter will only occur when electrons are liberated from the metal creating a flow of electric current. However, if the sodium plate is exposed to light, an electric current will flow and this will register on the meter. By blocking the light from illuminating the sodium plate, the current will then stop. When the amount of light striking the plate is increased, the amount of current also increases. If various colours of light are tested on the sodium plate it will be discovered that violet and blue light causes current flow.
However, colours of light toward the other end of the spectrum (red) do not ...
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... the cathode equals their potential energy at the anode. Emax = -qVo, where Vo is the magnitude of the stopping potential in volts (J/C), and q is the charge of the electron (-1.60 x 10-19C). The joule is too large a unit of energy to use with atomic systems, therefore the electron volt (eV) is used instead. 1 eV = (1.60 x 10-19C) (1V) = (1.60 x 10-19C)
(V). Also, 1 eV = 1.60 x 10-19J. The results from this experiment will show that higher frequency radiation will have higher stopping potentials, and lower frequency radiation will have lower stopping potentials, holding true to Einstein's hypothesis.
Conclusion The photoelectric effect revolutionized the way the nature and behaviour of light is understood. It also saw the dawn of modern physics with the use of the Particle Theory, and it catapulted Einstein to Nobel Prize-winning status.
Today, the phenomenon has many practical applications such as alarm systems that activate when the flow of light is interrupted.
Photoelectricity also helps explain the physics of photosynthesis, by which plants make their own food. It's truly evident that the photoelectric effect and its explanation played an important historical role in science.
Light dependent reactions are the effects that occur in photosynthetic organisms in response to solar energy and is the initial process of photosynthesis. Another name for light dependent reactions is, non-cyclic photophosphorylation. The site of these reactions occurs within the chloroplast in what is known as the Thylakoid membrane. Light is absorbed by something called photosystems (PSI AND PSII) and is part of all photosynthetic organisms. The light energy collected in this process will later become chemical energy. The process starts out with the excited electrons in PSII and then PSI. These electrons become excited from the absorption of light. The high energy electrons in PSI go down something called the electron
The Calvin cycle occurs in the liquid of the chloroplasts of the plant, called the stroma.
Photodynamic therapy (PDT) has proven to be an encouraging therapy used in treating metastatic melanoma skin cancers. There are three requirements for PDT to be successful: a photosensitizer (PS), light, and oxygen in the tumor site. One problem with current PS is their inability to penetrate deeply. A suggested PS is chlorin e6 (Ce6) because of its high singlet oxygen quantum yield, bright fluorescence, and rapid clearance from the body. However, there are some challenges with Ce6 as it is not water soluable, has poor pharmacokinetics, and lack of the ability to specifically target the tumor. To help solve these challenges, Ce6 was conjugated to carbon dot (Cdot). This helps Ce6 be more water soluble and extend the half life in the blood. Additionally, Cdot indirectly excites Ce6 by Forster fluorescence resonance energy transfer. Cdot is also nno-cytotoxic, and has a cheap
Schrodinger devised what is known as the “Schrodinger’s Cat Paradox” in 1935. It was one of his later discoveries and was worked on after extensive correspondence with Albert Einstein. Dr. Schrodinger earned his PhD in physics in 1910 from the University of Vienna in Austria. Though the Schrodinger Cat thought experiment is well known, Schrodinger earned his Nobel Prize for work on the movement of electrons (known as ‘Schrodinger’s Wave Theory’) in 1927. The Schrodinger’s Cat paradox was devised while he worked at the University of Graz in Austria.
For years scientists had known that if an electric current was passed through a vacuum tube, a stream of glowing material could be seen, however no one could explain why. Thomson found that the mysterious glowing stream would bend toward a positively charged electric plate. Thomson had the idea, and was later proven correct that the stream was in fact made up of small particles, pieces of atoms
He kept the gasses in glass tubes and at the end of each side of the tube, laid an electrode. The electrodes were connected to electricity, and on one side the electrode was charged positively, and on the other side it had a negative charge. He found that it formed a glowing beam, which he called a cathode ray. He knew from previous knowledge that opposite charges attract and like charges repel, so he hypothesized that a cathode ray is a flood of small negatively charged particles moving at a high speed, because the rays flowed in the direction of the positive electrode, which meant that the rays must be negative. To test his findings, he used an experiment where he measured the ratio of charge of an electron to its mass and he discovered that the ratio is constant, and that this ratio did not depend on the kind of gas nor the type of metal used for the electrodes. Then shortly after, U.S physicist Robert A. Millikan conducted an experiment where he had to find the amount of charge carried by an electron. He used the value he found and the charge-to-mass ratio of an electron that Thomson had discovered, to determine the mass of an electron. He was extremely close to the fact that is accepted today, which is that the electron carries one unit of negative charge, and its mass is 1/1840 the mass of a
Some physical entities such as light can display some characteristics of both particles and waves. Before the early 20th century, scientists believed that light was in the form of an electromagnetic wave. It wasn’t until the 20th century onwards that scientists found that light has properties of waves and particles. Scientists discovered different properties of light through experimentation and allowed them to determine that light actually has a wave-particle duality.
In spite of this uncertainty, Wheeler continues, quantum physics serves both practical and theoretical ends. The theories involved in quantum physics explain atomic structures, starlight, the earth’s radioactive heat, and the travels of particles (which are waves of energy, it would seem) between neutrinos and quarks. The vocabulary has gotten tougher; Wheeler clearly assumes his readers know what ‘particles’ and ‘waves’ mean when physicists use those “ordinary” words, let alone what they mean by neutrinos and quarks (41).
An important discovery in Chemistry is the Atomic Theory, John Dalton linked invisible atoms. Dalton’s atomic theory was based on the belief that atoms could be dignified by the differences in their masses. He first stated his theory in 1803 at the Royal Institution, the theory had six basic ideas : all matter is composed of atoms, atoms cannot be made or destroyed, all atoms of the same element are identical, and different elements have different types of atoms. Atomic Theory didn’t start with though John Dalton in fact it started with Democritus dating all the way back to about 460 B.C.. He believed that there were small invisible bodies from which everything is made of and travels in a void of space. He also rationalized the different laws of chemical combination during this time. Many, many, many years later in 1704 Newton came along and proposed a mechanical with small solid masses and that forces held atoms together. In 1803 Dalton said that, “All matter is composed of atoms and that they can’t be created nor destroyed, atoms of the same element are identical, chemical reactions can happen when atoms are rearranged and compounds are created from atoms of elements. His theory explained things that were unclear at the time. In 1894 G.J. Stoney put out the idea that electricity was form of electrons. He started the idea of using symbols to represent the elements and he contributed to finding out the exact atomic weight. Later on in 1897 J.J. Thomson used a CRT to experimentally find out the charge of an electron. He did this by multiplying 1.79 by 10 8. In 1900 Planck used the idea of quanta to clarify hot glowing matter. In 1903 Nagaoka suggested a “Saturnian” model of atoms with flat rings of electrons circli...
At the moment that Max Plank discovered the light-quanta in 1900, the modern quantum physics had been started. Several years later, Niels Bohr discovered the quantum-leap and it brought out the quantum theory. The quantum theory, creates the totally mystery world, redefining our understanding of the reality. It seems to be a disaster that the classical physics may be totally wrong. No one can predict where a quantum will go before you take a measurement under the principle of uncertainty. This leads to a contrast to what we believed in classical physics. (Davies, 1982) Fortunately, this inte...
The reason light intensity is being used compared to whether or not a plant needs light. It is because The experiment wants to show that the rates of photosynthesis will vary according to how much light from a light bulb will be trapped in. the chloroplasts, in the leaf. The more energy trapped the more efficient a chemical reaction can take place and the speed of photosynthesis will increase. There are many things which can affect the photosynthesis of a plant such as light intensity, temperature and carbon dioxide levels.
The purpose of this research project is to evaluate and explain the use of photo-elicitation as a method for data collection, when researching early childhood socialisation and identity. I will reflexively describe how participants feel about their early socialisation and if it has affected how they see themselves today. This research paper will be discussing what photographs participants have chosen, how I conducted my photo-elicitation interview and how participants engaged with the photographs during the interview. I will conclude with a critical discussion of visual methods and photographs. In addition to, what purposes visual methods serve as prompts within the interview process.
Electroplating Experiment Aim To find the amount copper gains or loses on the electrodes using different amounts of current each time during electrolysis. How the changing of current affects the electroplating of copper. Introduction Electroplating is generally carried out in order to improve the appearance or corrosion resistance of the surface of a metal by electrodepositing a thin layer of metal ion on it. The metal substrate to be coated is made by the cathode in an electrolytic cell. The cell used in electroplating contains an electrolyte which is usually an aqueous solution containing a reasonably high concentration of an ion of the metal which is to be electroplated on the surface.
From a discovery made by one of his associates, he patented the Edison effect (now called thermionic diode), which is the basis for all electron tubes. Edison will forever be remembered for his contributions to the incandescent light bulb. Even though he didn't dream up the first light bulb ever crafted, and technology continues to change every day, Edison's work with light bulbs was a spark of brilliance on the timeline of invention.
Faraday continued his electrical experiments. In 1832, he proved that the electricity induced from a magnet, voltaic electricity produced by a battery, and static electricity was all the same. He also did significant work in electrochemistry, stating the First and Second Laws of Electrolysis. This laid the basis for electrochemistry, another great modern industry.