Photoelectric effect

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    Photodetectors Essay

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    incoming photon, which is detected by an electronic circuit, while thermal detectors convert optical energy to heat, which then generates an electrical signal.3 Herein, two types of photodetectors are examined: a PD and a PMT. Although both detectors detect light by converting incident photons to electrical signals, they differ in the way they achieve this. The PD is a p-n junction semiconductor device that generates current when the photodiode absorbs a photon of sufficient energy. This process creates an electron-hole pair through a photoelectric effect. The holes move to the anode while electrons move to the cathode creating a photocurrent. PDs have fair sensitivity and relatively fast response times, but have some limitations due to noise.4 A PMT is a single tube that consists of a photocathode, a series of dynodes, and an anode. Arriving photons strike the photocathode, from which an electron is ejected as a consequence of the photoelectric effect. This electron is directed to an electron multiplier though a secondary emission process.4 Thus, the large number of electrons arriving at the anode creates a sharp current response that is detectable. Like PDs, PMTs also have relatively fast response times, but they are exceptionally sensitive, allowing them to be used in single photon studies.4 In order to study these two photodetectors, we analyzed three properties: sensitivity, shot noise, and gain. The sensitivity, S, is defined as the measure of the average current, I,…

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    Isaac Newton's Theory

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    to accurately predict its behaviour. His ‘imaginary’ discrete energy packets had no place in this structure. Planck’s equation was not, at first, very popular. The rest of the physics community had the same problems with it as he did, the fact that he had to use a mathemagical trick to get the right curves for blackbody radiation. Light did not come in quanta, so there had to be a better equation waiting to be found. Albert Einstein had other ideas. …That Changed Reality The Photoelectric Effect…

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    This is what is called constructive interference. The Classical Mechanic then directed Alice’s attention to the area of the water where the water was practically undisturbed. In this case, the water from one gap created a rise in the water as Alice had previously observed. This time, however, the water from the second gap created a trough in the water’s surface. The Classical Mechanical explained to Alice that, in the case that one wave goes up above the surface of the water and one goes below…

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    Albert Einstein's Photoelectric Effect

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    Einstein developed the theory that light travels at the same speed no matter the “frame of reference” which contradicted Galileo’s previously believed theory of relativity, giving the scientific community a different idea to ponder (Hayden 12). Albert discovered that the universe was constantly expanding, later proven by Edwin Hubble, which discredited the previous view that the universe was static or never changing, altering the scientific world’s past beliefs (Biography.com 14). One of…

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    “labels” and became very famous for his scientific knowledge. When Einstein was 16 years old, he always wondered what it would be like to ride his bike on a beam of light, 10 years later he came up with a special theory of relativity, which lead him to find out that light always travels at the same speed (which is 186,000 miles/second). Albert Einstein’s career, beginning with an extensive education through physical science, had a lasting influence on the photoelectric effect, Special/General…

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    First, Brody highlights some effects of environmental degradation such as the difference in salt content in soil and drought. For example, the habitats of plants have changed so much that it delays their natural rate of growth (“Fears, Not Facts …”). However, she further describes that such conditions play no effect in G.M.O. crops because they contain devised characteristics of tolerance that ensure them to have a higher probability of long life and, thus, a better chance in a large production…

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    Effects Of Loss Essay

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    The Effects of Loss Tupac Shakur once said, “Death is not the greatest loss in life. The greatest loss is what dies inside while still alive...” This quote states, that the things one may lose in life can cause great affect on the emotional and mental well-being of a person. How loss affects a character can be seen in both film and in books. The film, Shenandoah, which takes place in 1965 in America during the Civil War, reflects upon the Anderson family who tries their best to avoid the…

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    Global Risk

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    been blamed for causing some of the worst problems based on various fields such as social, political and economic effects that are proving difficult to control (Nelson, 2003). Some key factors that are expected to change due to environmental stress include rise in water level and climate change that will prove difficult to control. Water requirements are expected to change tremendously and push to a percentage of about forty percent. Food is one of the most critical aspects that should be…

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    is the belief it has an effect on IQ. For years the public has been informed about how marijuana has a negative effect on your IQ. As a teenager you are required to take a health class and in the class you are taught about the effects of marijuana. One of the side effects that teenagers are told is if they use marijuana as a teenager it will have a dramatic impact on their IQ, in a result, they will do poorly…

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    take long for the physical effects such as fatigue, nervousness, and increased heart rate to start and take effect. Many internal effects like higher blood pressure take effect much later than the physical effects and many times affects the health in a negative way. If a person does not start to relieve their stress by relaxing and lowering his blood pressure, could cause some severe long term damage to his health. Stress can also cause a person to have a lot of sleepless nights that will…

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