Do you know Light allows you to see? How? Do you see in the dark or at night? This topic will enlighten you on light.
What is Light? Light is a form of "energy" that enables us to see. It can also be called "Radiation(meaning rays spreading from a certain object, e.g Sun, Torch) or EM(ElectroMagnetic) Radiation."
We see things in daytime because of Light, you know a counterfeit/fake money when you use light, etc.
Light can be Visible(ones we see with naked eyes like Sun, Torchlight, etc) or Invisible(ones we don't see with naked eyes like, X-rays, Microwave, Radio wave, etc). It can be long or short. Mostly all light are dangerous when their intensity increases.
Sources of Light:
We can get light from
1. Natural Sources: e.g Sun, Stars, etc.
a) Luminous: gives light naturally. e.g Sun, Diamond, FireFly, Jelly Fish, etc.
b) Non-Luminous: do not give light naturally. e.g Moon, etc.
2. Artificial Sources: Bulb, Torch, etc.
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Rectilinear Propagation of Light:
The word "rectilinear" here means "on a straight line," while "propagation" means "to travel."
Hence, this phenomenon tells us "that light travels on a straight line." It can be showed by>
a) Formation of Shadows.
b) Formation of Eclipses.
c) Principle of Pinhole Camera, etc.
A) Formation Of Shadows:
hope, you've seen a person walking pass a Projector's light maybe on a Crusade ground? What do you see? Yes, his/her shadow. Walk under the Sun, you will see your shadow cast on the ground. Flash someone light at night, you'll see his/her shadow straight on the wall. This is to tell you that because light travels in a straight line that it can cast a shadow straight to an object.
B) Formation Of Eclipses:
many hear about Eclipse but do not know what it's all about.
Eclipse occurs when Sun, Earth, & Moon align in a straight line that the light from the Sun is difficult to be seen. In our universe, ..

we have 3 bodies/objects that must be in a straight line before an Eclipse takes place. They are "the Unblocked, the Blocking, the Blocked."
Two Types of Eclipses:
1. Solar Eclipse(Eclipse of the Sun): occurs when the Moon(the blocking) blocks the Earth(the blocked) from the Sun(the unblocked). Hence, the Moon is between the Sun & the Earth. It has three types >
a) Total Eclipse: when the Moon blocks the light totally from reaching the Earth.
b) Partial Eclipse: when the Moon blocks the light partially from reaching the Earth.
c) Annular Eclipse: when the Moon blocks the light yet the light takes the shape of the moon in ring forms to reach the Earth.
2. Lunar Eclipse(Eclipse of the Moon): occurs when the Earth(the blocking) blocks the Moon(the blocked) from the Sun(the unblocked). Hence, the Earth is between the Sun & the Moon. It's of two types >
a) Total Eclipse
b) Partial Eclipse
See attached Photos below for Eclipses.
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.. lastly on this topic, before we talk on the "Pinhole Camera." Lets look at light in Dual(two) Nature. Light behaves both as a Wave(electrons/
electro) & as a Particle(magnets/magnetic), which gives it another name as "ElectroMagnetic Radiation."
The TV-Shows/News you sit at your homes watching is Light in Dual Nature (Light travels as Wave to your TV, gets magnetized by it & then forms the Particle that displays the shows/news you watch).
You are snapped by a Camera(i.e light in wave nature) & got a photo printed out(i.e light in particle nature).
C) Principle of Pinhole Camera: Pinhole Cameras are those old Cameras you peep your eye into its small hole before you snap. It shows light travels in a straight line. Light travels as a Wave through the camera, magnetizes every object(you) along its way back to the Camera, then forms a Particle which displays your photo on the Camera's Screen.
Now you know why your Selfies(photos) is powered by Light Energy.
We can use Physics and apply in building technology.
My question is, where are our Professors?
Cc: Lalasticlala, over to you!

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