LESSON
1: THE
FACTS OF
LIGHT
*LIGHT IS
AN ENERGY
THAT WE
CAN SEE.
*THE SUN IS
OUR MAIN
SOURCE OF
ENERGY.
*LIGHT
TRAVELS
FROM ITS
SOURCE IN
STRAIGHT
LINES IN
ALL
DIRECTIONS.
*THREE
SOURCES OF
LIGHT
ENERGY IS
FROM THE
SUN, FIRE,
AND
ELECTRICIT
Y.
2
NATURES
OF LIGHT
1. WAVE
(UNDULATO
RY)
THEORY- IT
EXPLAINS
THAT LIGHT
HAS A WAVE
MOTION
THAT
STARTS
FROM A
VIBRATING
BODY AND
IS
TRANSMITT
ED AT HIGH
SPEED.
*CHRISTIAN
HUYGENS- A
PROPONENT
OF THIS
THEORY
WHO
EXPLAINED
THE
REFLECTION
OF LIGHT
USING
WAVE
MOTION. HE
ALSO
PROPOSED
THAT LIGHT
CONSISTS
OF A SERIES
OF WAVES
WITH THEIR
WAVE
FRONT AT
RIGHT
ANGLES TO
THE PATH
OF THE
RAYS.
2. QUANTUM
THEORY OF
LIGHT-
STATES
THAT LIGHT
IS
COMPOSED
OF BUNDLES
OF WAVE
ENERGY
CALLED
PHOTONS
OR QUANTA
THAT
BEHAVE
LIKE
PARTICLES
RATHER
THAN
CONTINUOU
S WAVES.
*ALBERT
EINSTEIN IS
THE
PROPONENT
OF THIS
THEORY.
Lesson 2:
Sources of
Light and Its
Propagation
Optics- studies
the behavior
and properties
of light.
Light- is a
combination of
both electrical
and magnetic
energy that can
travel at
varying
velocities in
various media.
*Luminous
objects- are
objects that
emit or send
off their own
light. They
tend to radiate
heat as an
effect of being
luminous and
can store
energy.
Examples are
sun, stars, light
bulb, lamps,
lasers, and
campfires.
*Non-
luminous
objects- are
those that
cannot emit
their own light.
Examples are
moon, cars,
buildings.
Incandescence-
when object is
heated at a
very high
temperature,
say around 470
degree celcius,
it starts to glow
and become
dull red in
color.
*Luminescenc
e- used to
describe a
process by
which light is
produced other
than heating.
2 forms:
1.
Fluorescence-
refers to the
release of light
that lasts no
more than
about 10
nanoseconds
after it begins.
Example to
this is the light
bulb.
2.
Phosphorescence
- refers to the
release of light
that lasts
longer than 10
nanoseconds.
Example to
this is the
glow-in-the-
dark toys.
Transparent-
materials such
as air, glass,
water, and
clear plastic
permit the
passage of
light.
*Opaque-
block the light
examples are
woods,
concretes,
metals, and
flesh of
animals.
Translucent-
objects that
allow only
some amount
of light to pass
through.
Photometry- a
branch of
optics that
deals with
illumination
and the amount
of brightness
that a light
source
possesses.
Lesson 3:
Risks and
Hazards of
EM
Spectrum
1. EM
Radiation- a
kind of
radiation
including
visible light,
radio waves,
gamma rays,
and x-rays, in
which electric
and magnetic
fields vary
simultaneously
.
2. Ionizing
Radiation-
have enough
energy that to
remove tightly
bound
electrons from
the orbit of an
atom, causing
severe damage
in living
organisms.
Ex. X-rays &
Gamma rays.
3. Atomic
Sources of
Radiation- is
created by
changes in the
state of an
atom.
Example, the
disturbances in
the electric and
magnetic fields
permeating the
universe arise
from the
vibration of
atoms or
excitation of
electrons.
Uses and
Harms:
Radio waves-
Broadcasting
and
Communicatio
ns
Microwaves-
Cooking,
Satellites
Transmissions,
Mobile Phone
Infrared Rays-
Heaters and
Night Vision
Equipments ;
skin burns
Visible Lights-
Optical fibers
and
photography
Ultraviolet-
Damage to
surface cells
and blindness
X-rays- Cancer
Gamma Rays-
Cancer and
Mutation
