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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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Characteristic X-ray spectrum | Atomic and molecular physics | X-rays

Characteristic X-ray spectrum

Line spectrum

  • The methods of producing characteristic X-rays are:
  • In this method we use element as a target in the X-ray tube and electrons are bombarded directly on it.
  • For each target there is a minimum potential below which the line spectra do not appear, and this critical potential difference is different for different element.
  • In this method the primary X-rays from a hard X-ray tube allow to fall on the element.
  • The primary X-rays must be harder than the characteristic X-rays to be produced.
  • The peak obtained in the X-ray spectrum gives the line spectrum, which is the characteristic of the element.

  • Moseley used the potassium ferocynaide as a crystal and photographic plate as a recording medium in place of ionisation chamber in the X-ray spectrometer.
  • He obtained line spectrum by using 30 different targets in tubes and concludes the following:
  • The spectrum obtained by graph has two different groups. The series of lower wavelength is K-series and of higher wavelength is L-series.
  • Since the linear spectrum depends on the nature of target material and therefore it is also called characteristic spectrum. The number of lines in line spectrum depends on the nature of nucleus and the applied voltage.
  • It is easier than optical spectrum, and are same for all types of elements.
  • The frequency of a particular line spectrum increases with the position of element in periodic table.
  •  = a (Z - b)2
  • Above equation is known as Moseley’s law
  • a and b are constants
  •  frequency of line
  • Z atomic number

Origin of characteristic X-ray spectrum

  • According to Moseley, when electron jumps from higher level nf to lower level ni, then frequency of emitted X-ray.

  • Here R is Rydberg’s constant, b is screening factor and c is velocity of light
  • When high energy electron are bombarded on a target nuclei, then attacking electron removes one electron from K-shell.
  • This empty space of K-shell is filled by another electron of L or M shell and hence the spectrum lines of K-series are formed.

  • If electron jumps from L to K shell, then Kα line is formed, and if electron jumps from M to K shell then Kβ line is formed.
  • Similarly L, M and other series can be formed.

Kossel's diagram

To know more about characteristic X-ray spectrum, please click on https://youtu.be/9rNnu2BzzrE
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