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National Bird Day: Why Birds Matter to Us

National Bird Day is celebrated every year on 5 January . This day is observed to spread awareness about birds, their importance in nature, and the need to protect them. Birds are beautiful living beings and play a very important role in keeping our environment healthy. Origin of National Bird Day National Bird Day was first celebrated in the year 2002 . It was started by bird lovers and environmental groups to protect birds from dangers like deforestation, pollution, and illegal hunting. The main aim of this day is to teach people, especially students, why birds are important and how we can help save them. Why Is National Bird Day Celebrated Every Year? National Bird Day is celebrated every year because many bird species are disappearing due to human activities. Cutting trees, using plastic, pollution, and climate change are harming birds and their homes. This day reminds us that: Birds need protection Nature should be respected Everyone has a responsibil...
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Moseley’s law | Atomic and Molecular physics

Moseley’s law

  • According to it, the frequency of a spectral line in X-ray spectrum varies as the square of the atomic number of the element emitting it.
  • If 𝜈 is the frequency of spectral line in X-ray spectra and Z is the atomic number of element, then
  • 𝜈 = Z2 ⇒ √𝜈 ∝ Z
  • or √𝜈 = a (Z– b)
  • Here (Z –b) is the effective atomic number of emitting element and b is the characteristic constant or screening constant.

Importance of Moseley’s law

  • The characteristic property of an element depends on their atomic number, not on their masses.
  • So the position of some elements in periodic table was rearranged.
  • On the basis of Moseley law some new elements of periodic table was discovered like Hf (72), In (61), Re (75) etc.

Explanation of Moseley’s law on the basis of Bohr’s theory

  • The energy of electron in n1 and n2 orbits are given by

  • Since the positive nucleus is screened by rest of the electrons.
  • Therefore we use atomic number (Z– b) in place of Z.

  • If Z is very large, b1 ≈ b2 ≈ b

  • For Kα line, n1 = 2 and n2 = 1

  • For Kα line, a = 3Rc/4 and b = 1
  • Here R is Rydberg’s constant, and c is velocity of light.
To know more about Moseley's law please click on the link for English and click on the link for Hindi
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