The nature of light

1. THE NATURE OF LIGHTTHE NATURE OF LIGHT

2. ACTIVITY
With a partner, list down all the possible sources
of light.

3. MAYBE YOU HAVE THOUGHT OF…

4. LIGHT PRECEDES SIGHT

5. THEN WHAT IS
LIGHT?

6. BEFORE WE DEFINE LIGHT…
Let’s talk about the electromagnetic spectrum
Trace the historical development of the theories
that explain the nature of light

7. A REVIEW OF
ELECTROMAGNETIC WAVES
These are waves
produced by oscillating
charges.
They can travel through
a vacuum or material
substance.
They are transverse in
nature.
There are seven
identified classes of
electromagnetic waves.

8. THE ELECTROMAGNETIC
SPECTRUM

9. A CLOSER VIEW ON THE EM
WAVES

10. RADIO WAVES
These include TV signals
and AM and FM radio
signals.
They have the longest
wavelength in the
electromagnetic spectrum
which may be several
kilometers.
They have also the least
energy in the family of
EM waves.

11. MICROWAVES
EM waves that have
wavelengths in the range
of centimeters.
They are used to carry
communication signals
over long distances (space
probes).
Also used in cooking.

12. INFRARED WAVES
EM waves that have
wavelengths slightly
longer than wavelengths
of red visible light.
The warming effect of the
sun is an example of
infrared radiation.
Can be used to produce
detailed image of objects
(weather forecasting)

13. ULTRAVIOLET WAVES
Invisible waves that lies
just beyond the violet
light
Has higher energy and
frequency but shorter
wavelengths compared to
visible light.
Has enough energy to
pass through clouds.
UV can be used to kill
germs and disinfect
objects.

14. X-RAYS
EM waves with
wavelengths less than
10
-8
m
Highly useful in medical
imaging
Contain a lot of energy
that may give
detrimental effects to
tissues

15. GAMMA RAYS
EM waves with the
highest energy and
frequency
Shortest wavelength
Most penetrating
Exposure to these rays
may pose danger
Can be used to treat
cancer

16. THE NATURE OF LIGHT

17. DEBATES ON THE NATURE OF
LIGHT
Particle or Corpuscular Theory
Wave Theory of Light
Dual Nature of Light

18. Light behaves
as a
PARTICLE.

19. EVIDENCES FOR WAVES

20. THOMAS YOUNG AND THE
DOUBLE SLIT EXPERIMENT

23. POLARIZATION OF LIGHT

26. EVIDENCE FOR PARTICLES

27. PHOTOELECTRIC EFFECT

30. THE DUAL NATURE
OF LIGHT

31. LOUIS DE BROGLIE

32. LIGHT HAS DUAL NATURE