newton
TRANSCRIPT
A long time ago …
Aristotle (384 - 322 B.C.), an ancient Greek, thought that we see the world by sending “something” out of our eye and that reflects from the object.
In the17th century, two scientists had different views about the nature of light …
Christian Huygens (1629/1695)
Isaac Newton (1643/1727)No! Light is
particles
Light is waves
In the 17th century, some properties of light were already known. For example:
• Light has different colours.• Light can travel through a vacuum.• Light can be reflected and refracted.
Newton was the “winner”…(at that time!)
Why does light have different colours?
Why does light travel in straight
lines?
Why can light travel through a vacuum?
Isaac Newton observed that a thin beam of sunlight hitting a glass prism on an angle creates a band of
visible colors that includes red, orange, yellow, green, blue, indigo and violet.
This occurred because different colors travel through glass at different speeds.
So he proposed his “particle theory of light” to explain the characteristics of light.
I think light is a stream of
tiny particles called
Corpuscles
(source: “Opticks”, published by Isaac Newton in 1704)
1. Light consists of very tiny particles known as “corpuscles”. Every elumiscent source like the sun or a candle emit these corpuscles.
2. These corpuscles on emission from the source of light travel in straight line with high velocity in all possible directions.