Lecture 2 Properties of em waves

This ppt discusses the properties similar to all member of electromagnetic spectrum.

1. LESSON 2:
PROPERTIES OF
ELECTROMAGNETIC
WAVE

3. Objectives:
At the end of the lesson, you will
be able to
•Describe the main components of
the electromagnetic spectrum.
•State the properties of ALLEM
waves.

4. •Perhaps the greatest theoretical
achievement of physics in the 19th
century was the discovery of
ELECTROMAGNETIC WAVES .

5. •The first hint was an unexpected
connection between electric
phenomenaand the velocity of light.

6. WHO CAME UP WITH THE IDEA OF SPEED
OF LIGHT?
•Galileo attempted to record the
time between lantern signals but
was unsuccessful because the
distance involved was too small
and light simply moved too fast
to be measured this way.

7. WHO CAME UP WITH THE IDEA OF SPEED
OF LIGHT?
•Around 1676, Danish
astronomer Ole Roemer
became the first person to
prove that light travels at
a finite speed.

8. Roemer’s Method of Calculation

9. What are Electromagnetic Waves ?
•If you have ever tuned in to listen
to a radio, spoken on a handphone,
turned on a light, had an X-ray
taken, felt the warmth of sun on
your skin.
•You have experienced
electromagnetic wave

10. Electromagnetic waves
•A moving charge
creates magnetic field.
•A changing magnetic
field causes a changing
electric field.
Image credit:
http://www.school-for-
champions.com/science/magnetic_field_movin
g_charges.htm#.VThZiyaKCM8
Image credit:
http://electrical4u.com/faraday-law-of-
electromagnetic-induction/

11. ELECTROMAGNETIC WAVE is caused
by vibrations of both fields.

12. Electromagnetic wave
Produced by Simultaneous vibration
Electric field
Magnetic field
Electric field
Magnetic field
http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=52

13. Wavelength of Electromagnetic Waves

14. Hence this is the complete EM wave spectrum (the waves
below in ascending order of wavelength;
descending order of frequency )
Gamma
rays
x-rays Ultra-
violet ray
Visible
light
Infra-
red ray
Microwave Radio
wave
Highest f
Shortest λ
Lowest f
Longest λ

15. Properties of EM Wave
1.All electromagnetic waves
are transversewave

16. TRANSVERSE VS. LONGITUDINAL

17. 2.They do notrequire any medium to
travel through, they can travel in an
empty space or vacuum.
Vacuum; a space containing nothing at all,
Atoms are 99.999999999999% empty space.

18. 3.They travel at the speed of
3x10
8
ms
-1
in vacuum (recall: speed of
light light is also an EM Wave)

19. 4. They can all bereflected or
refracted.

20. 5. They can all beemitted or
absorbed by matter.

21. 6. They all obeythe wave
equation
Where v= speed of wave (m/s)
f= frequency of wave (Hz)
λ= wavelength (m)
v =f xλ

22. 7. Their SPEEDdo not change as
they pass from one medium to
another. However, both their
FREQUENCYand WAVELENGTH
will change.
v=fxλ

23. 8. It carry no mass but it carry
energyfrom oneplace to
another.

24. 9.They are all of neutral charge
as all of them oscillate with
electric and magnetic field
perpendicular to each other.

25. Waves
Longitudinal Waves Transverse Waves
Electromagnetic Waves
Properties
Electromagnetic Spectrum
Radiowave
Microwave
Infra-Red
Light
Ultra-Violet
X-ray
Gamma ray
Applications
Sound waves
Classified into
Comprises of
Overview of EM waves

26. TRUE OR FALSE:
1.Electromagnetic waves carry energy.
2.An electromagnetic wave is a
longitudinal wave.
3.Electromagnetic waves can travel in an
empty space.
4. Sound waves are electromagnetic
waves.
5. Different colors of light have the same
amount of energy.

27. LET’S CHECK!

28. 1.Electromagnetic
waves carry energy.
TRUE OR FALSE:

29. TRUE OR FALSE:
2. An electromagnetic
wave is a longitudinal
wave.

30. TRUE OR FALSE:
3.Electromagnetic waves
can travel in an empty
space.

31. TRUE OR FALSE:
4. Sound waves are
electromagnetic
waves.

32. TRUE OR FALSE:
5. Different colors of
light have the same
amount of energy.