Grade 9 – lesson 1
WHAT IS LIGHT?
NB TERMS:
1. Wave length
(Nanometers)
2. Frequency
3. (Hertz)
WHAT IS LIGHT?
 The visible region: the part used by your eyes to see
HTTPS://WWW.YOUTUBE.COM/WATCH?V=BUYEQA_-OJK
LIGHT IS
ENERGY
 Kinetic energy: moves from one
place to another (radiant energy)
 Carries energy away from sun/light source
 Can be changed from one energy to another
LUMINOUS VS NON-LUMINOUS OBJECTS
 Luminous: objects able to make their own light (produce light)
 Non-luminous: objects that reflect light
Vs
.
Light travels VERY FAST – around
300,000 kilometres per second.
• At this speed it can go
around the world 8 times
in one second.
• Light sources radiate light
when they receive energy and
their particles become excited
• Light travels much faster than
sound.
• For example: Thunder and
lightning start at the same time,
but we will see the lightning
first.
Light travels
in straight
lines
Laser
RAYS AND BEAMS
HTTPS://WWW.YOUTUBE.COM/WATCH?V=LOIGOT88AQC
 https://www.youtube.com/watch?v=lOIGOT88Aqc
HTTPS://WWW.YOUTUBE.COM/WATCH?V=JHBC39XZVNW
 You do not need
to do the activity
at the end of the
video however if
you are interested
and would like to
play you can go
to KHAN
ACADEMY and
find the activity.