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chemistry.pptx

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chemistry.pptx

  1. 1. Branch : Electrical Engineering Subject : Chemistry Students : Patel Preet - 226120309097 (96) Patel Sakshi - 226120309100 (99) Patel Sanjana - 226120309101 (100)
  2. 2. How we see colors [black body radiation]
  3. 3. What is black body radiation ▹ Radiation emitted by an object due the increment of their temperature compare to its surrounding is called Black-Body radiation and that object is known as Black-body. ▹ Sun is perfect example of black-body because it can Emit radiation of any wavelength. ▹ The
  4. 4. Effect of Temperature ▹ Black body absorbs the radiations . ▹ If surrounding is cold and black body is hot due to absorbing radiations so the heat energy will flow from the black body to surrounding in form of electro magnetic radiations.
  5. 5. Colours ▹ When black body can absorb the radiation in limits and it reflect the left radiation back . ▹ This reflected radiation is in wave form , so there are radiations which have different wave length and frequency. ▹ That is the reason why we can see different colours easily. ▹ Scientist did an experiment for this , they gave heat energy to a metal box and at different temperature that box gains different radiation. Because of the different radiation that box changed colour .
  6. 6. ▹ From performing the experiment scientist noted that if we increase temperature , black body will radiate higher radiation ▹ It means if we increase the temperature the wave length of the radiation will decrease ▹ After this theory famous scientist Planck gave a statement “ energy is discontinuously radiated in discrete wave packets.” snf equation between energy and frequency of photons . Which is E= hµ where h is Planck’s constant. (6.626 x 10^-34)
  7. 7. Applications ▹ We should wear black dresses during winter because subject which is black can absorb more radiation than others. ▹ To analysis the planet’s heat and atmosphere from earth. ▹ Red color scatters the least as it has the greatest wavelength. So red light is able to travel the longest distance through the fog, rain, and air particles. That is why the red color is used in danger signals; not because it is more attractive and common. ▹ Black body can gain energy from light so there are blue lights
  8. 8. In freezers so products cant gain the energy or heat  We use radium coloured straps on road breakers because we can see them by reflected radiation of the lights . Which leads to less accidents.  Blue led to scan finger prints and doctors also use to check up the patient.  With Blue Dim light we can save electricity because blue color needs less energy , it has less frequency and also its not so bright so as dim light it is perfect.
  9. 9. THANK YOU

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