Electro magnetic resonance & its relation with frequency,wave length and wave number

modern pharmaceutical analysis..M pharm 1st year.dept of pharmaceutical analysis.

1. Electromagnetic radiation & its relation with frequency,
wavelength, wave number
Submitted by
P sohail khan
M pharm 1
st
year
Pharm.analysis

2. Radiant Energy is the energy transmitted from
one body to another in the form of radiations .
The term radiation includes electromagnetic
vibrations ranging from the electric waves of low
frequency through ultra violet rays, visible
spectrum and infrared rays to high frequency
X -rays and γ-ray

3. “Electromagnetic radiation is thus a type of energy
that is transmitted through space at enormous
velocities. Radiant energy has wave nature and
being associated with electric as well as magnetic
fields, these radiations are called
electromagneticradiations.”

4. Electromagnetic Spectrum

5. 5
ELECROMAGNETIC SPECTRUM
•Electromagnetic waves are
formed when an electric
field(blue arrows) couples
with a magnetic field
(shown as red arrows).
•The magnetic and electric
fields of an EMR are
perpendicularto each other
and to the direction of the
wave.
•James Clerk Maxwell and
Heinrich Hertz are two
scientists who studied how
electromagnetic waves are
formed and how fast they
travel.

6. 6

7. 7
Fig. 6-6
Visable light
spectrum
Full range of electromagnetic radiation
l(nm) f (hertz)
1 nm = 10
-9
m

8. Properties of EMR
EMR is a form of energy that is transmitted
through space at enormous velocity.
It does not require any supporting media.
It readily passes through vacuum than in
supportingmedia
EMR is said to have a dual nature (wave
&particle characteristic).

9. Wave properties of EMR
•It’s an alternating electrical and associated
magnetic field. (both electric and magnetic
component)
•These two components oscillate in planes
perpendicular to each other and perpendicular to
the direction of propagation of the radiation.

10. WAVE LENGTH (λ)
It is the distance between two successive maxima or
minima.
It is generally expressed in nm.
FREQUENCY (ν)
The number of wavelength units passing through a
given point in unit time is called frequency of that
radiation.
Frequency has a unit of reciprocal time, generally
expressed in cycles/ second or hertz or fresnel.
1Hz = 1 cycle/sec
1 fresnel = 10
12
Hz

11. WAVE NUMBER (V)
It is defined as number of waves /cm in vacuum.
V = 1/λ
Wave number is expressed in cm
-1
or Kaiser (K)
1 Kilo Kaiser (KK) = 10
3
K=1000/cm

12. VELOCITY (C)
Velocity of EMR depends on the medium through
which radiation is passing.
It is expressed in cm/sec, m/sec etc.
C= λ x ν
Velocity is inversely proportional to density of
medium.
Velocity if light in vacuum is 3x10
8
m/sec.

13. Particle nature of EMR
There are various wave properties like refraction
,reflection, reinforcement and destruction interference.
But the wave nature fails to explain phenomenon like
photo electric effect etc.
In order to explain such phenomenon it is assumed
that the EMR consist of a stream of discrete
packets(particles ) of pure energy called quanta or
photon .

14. Photonshave definite energy and travel in direction of
propagation of radiation beam with an equal velocity of
light c.
The energy of photon is proportional to frequency of
radiation and is related as
E = h ν
Where E = energy of photon in ergs.
ν= frequency of EMR in cycles/sec.
h = Planck’s constant = 6.624 x 10
-27
ergs sec.
= 6.624 x 10
-34
joules sec

15. A photon of low frequency (longer wavelength) has
low energy content than one of higher frequency
(shorter wavelength)
The intensity of beam is proportional to number of
photons/sec . propagated in the beam but is
independent of energy of each photon.

16. Relation of wavelength and particle
properties of EMR
According to plank if a transition occurs between
the energy states of a system such that a photon of
energy E is emitted or absorbed , the frequency νof
the emitted or absorbed radiation is given by
E = h ν
With this equation a particular λ of wave number
of frequency can be converted to desired units

17. RELATION BETWEEN FREQUENCY, WAVE
LENGTH & WAVE NUMBER
We know that
E = h ν……(1)
ν = c/ λ
Then,
E= h c/ λ……..(2)
We know that
V = 1/λ
Therefore, E=h c V…….(3)
We have
ν = c / λ
then, ν = c V or V = ν/c.
The above equation relates the frequency and wave number

18. Q: Calculate the wave number of radiation whose
wavelength is 5mµ

19. Q: Calculate the frequency of the radiation in
Hertz of wavelength 3500A
0

20. Q: Calculate the wave number of the lines of
frequency 4 x 10
14
Hertz

21. Q: The value of Plank’s constant is 6.62 x 10
-27
ergs sec per atom. Calculate the value in kcal
sec/mole

22. 5) Electromagnetic radiation with a wavelength
of 700nm is visible red light
a) what is the frequency and wave number of
this radiation
b) calculate the wavelength in A
0

23. Q: Convert 2000 A
0
to cm , cm
-1
, eV, erg, cal
and Hz

24. Q: Calculate the wave length of electron
moving with one third the speed of light

25. References
1) Fundamentals of analytical chemistry by Skoog
eighth edition page no 711 –715
2)Instrumental methods of analysis by Willard and
Merritt 6
th
edition page no 1 –4
3)Spectroscopy by BK sharma17
th
edition page no 1
-10