PHYSICAL SCIENCE

1. LIGHT

2. OBJECTIVES
At the end of the lesson, we will be able to:
a. Explain different theories of light,
b. Differentiate the classical from the modern theories of light,
c. Explain how light is reflected, refracted, absorbed and transmitted,
d. Differentiate reflection from refraction,
e. Explain how the medium by which light travels affects its
properties.

3. Key Concept
• Light is an amazing phenomenon that wonders man for
centuries. Light travels at a speed of about 300,000
kilometers per second and can travel around the earth 7.5
times in a mere one second. This property of light is utilized in
many technical applications such as optical communications
which transfer huge data in a very short time. In recent years,
research of such optical phenomenon that occurs in this
unbelievably short period of time, is becoming essential in
new research on different fields. The exact nature of visible
light is a mystery that continues to puzzle scientist from
different eras. Thus, speculations arise and different point of
views on how light behaves were always been an interesting
topic to discuss.

4. CLASSICAL AND MODERN THOERY OF LIGHT
• CORPUSCULAR THEORY OF LIGHT
• WAVE THEORY OF LIGHT
• ELECTROMAGNETIC THEORY OF LIGHT
• QUANTUM THEORY OF LIGHT

5. CORPUSCULAR
THEORY OF
LIGHT
According to this theory proposed by Sir Isaac Newton light
consists of tiny particles of matter called corpuscles that
move in straight lines.
When these corpuscles fall on a smooth surface, they will
be reflected.
Newton believed that light moves faster as it travels from
air into water.
An image of the object that we see is produced when these
particles enter our eyes.
These particles have different colors. Each color has a
different size of particles.

7. WAVE
THEORY OF
LIGHT
Christian Huygens proposed in 1678 that light is a wave.
Light is a series of waves travelling at different speeds in
different media.
These waves are not affected by gravity.
He further explained that reflection, refraction, and the
rectilinear propagation of light could be assumed if light
would be considered as a wave travelling a medium.
Further more, he insisted that the speed of light decreases
as it travels from air to water and vice versa.

9. ELECTROMAGNETIC THEORY OF LIGHT
• Proposed by James Clark Maxwell, this theory considers light as an
electromagnetic wave, having both electric and magnetic properties.
• https://www.google.com/search?q=electromagnetic+theory+of+light
&sxsrf=ALiCzsbjX90NBkP90oza44pd1hdCmF0amA:1672755376075&s
ource=lnms&tbm=vid&sa=X&ved=2ahUKEwjFqPKvy6v8AhUFaN4KHSj
BCdIQ_AUoAnoECAEQBA&biw=1366&bih=600&dpr=1#fpstate=ive&vl
d=cid:4a8fa0cd,vid:pj_ya0e20vE

11. QUANTUM
THEORY OF LIGHT
• Proposed by Max
Planck in 1900, this
theory states that light
waves travel as packets
of energy. He called
these packets of
energy as quanta or
photons.

12. • According to Planck's quantum theory, Different
atoms and molecules can emit or absorb
energy in discrete quantities only. The smallest
amount of energy that can be emitted or
absorbed in the form of electromagnetic radiation
is known as quantum

14. Reflection
• Reflection occurs when a wave hits
boundary between two media where
the wave speeds differ, but the wave
stays in the original medium instead
of passing into the second medium.
The angle of incidence equals the
angle of reflection.

15. REFRACTION
• refraction, in physics, the change
in direction of a wave passing
from one medium to another
caused by its change in speed.
For example, waves travel faster
in deep water than in shallow.

16. ABSORPTION OF
LIGHT
• Light absorption is the
process in which light
is absorbed by matter
and converted into
energy.

17. TRANSMISSION OF LIGHT
• The transmission of
light occurs when light hits an
object that is transparent or
translucent and light can
penetrate the material to
travel all the way through.
When light transmission
happens, it can be scattered or
refracted. Scattering happens
when light hits an atom and is
sent in all direction

18. ACTIVITY

19. b

21. b