From this presentation you can able to get some ideas on X-ray spectra.

1. Presentation
on x-ray
spectra
-P.SUBASRI,
ST.MARY’S COLLEGE,
THOOTHUKUDI.

2. Introduction
• Urey – Co worker’s analysed X-ray beam
from the x ray tube.
• They used different potential differences for
same target.
• Target-Tungsten.
• Graph was plotted for the intensity of the ray
against the wavelength.
• Finally from the graph they identified 2
spectrums.

3. 2 spectrums
Line spectrum
Continuous spectrum

5. Line spectrum
• For the P.D. 70kv – 2 sharp peaks are seen.
• The sharp peaks in the graph is called as line
spectrum.
• It is also known as the characteristic radiation.
• Line spectra is absent till the P.D. is greater than
a particular value.
• This characteristic spectrum is also constitute by
the superimposed lines on the continuous
spectrum.

6. Continuous spectrum
Smoothly varying curves represent the
continuous spectrum.
Main features:
1.For each anode potential there is a
minimum wavelength min below which no
radiation is emitted.
Above this critical value the intensity
increases rapidly with increasing wavelength.

7. Finally after reaching a maximum,it decreases
gradually.
Intensity never reaches zero this shows that
the radiation contains all wavelengths above
the minimum limit.
2.when the voltage across the X-ray
tube is increased min is shifted towards
smaller values.

8.  Duane and Hunt showed
min is inversely proportional to V.
vmax is directly proportional to V.
 This empirical law of Duane and Hunt is
expressed analytically as
eV=hvmax=hc/ min

9. explanation
eV is the kinetic energy of the bombarding
electron.
If the entire K.E. of the electron striking the
target is converted into energy of X ray
photon then eV=hvmax,according to Einstein’s
theory.
But
vmax=c/ min
eV=hc/ min

10. min=hc/eV
min is inversely proportional to V
Most of the electrons generating X-ray photon
give up only one part of energy.
Therefore most of the radiation is longer than
min.
Thus,the continuous spectrum is the result of
inverse of photoelectric effect,with eV being
transformed into hv.

11. Thank you