Light is nature's way of transferring energy through space.
Medium and the wave move in the same direction Sound needs a medium in order to travel from one point to another Sound travels in all directions and can go through most mediums Medium moves in the opposite direction that the wave is traveling Light doesn’t need a medium to travel from one point to another Light can only travel in a straight line and is not usually absorbed by the medium direction medium moves
AtomsAtoms and molecules, the smallest pieces of everything around us, are measured in nanometers.molecules A typical germ is about 1,000 nanometers. We can measure even larger things in nanometers, so a hair is about 100,000 nanometers wide. That is a lot of nanometers! Shaquille O’Neal, a very tall basketball player, is 2,160,000,000 nanometers tall.Shaquille O’Neal Nanometer is one billionth of a meter – Think about cutting a meter stick into a billion pieces…
Light travels much faster than sound. Thunder and lightning start at the same time, but we will see the lightning first. Light travels at a speed of 186,282 miles per second or 299,792 km per second) The speed of sound varies based on the medium it is traveling through and the conditions surrounding the medium.
How is Light Absorbed Absorption of light happens when atoms in an object absorb (take in and hold) the light waves For example: You are able to see a red apple because all of the other light waves are absorbed but red is reflected to your eyes.
We see things because they reflect light into our eyes Homework Why are we able to see objects ?
What is Reflection? Reflection – some or all of a wave bounces back into the first medium when hitting a boundary of a second medium When all the wave energy is reflected back instead of being transmitted, it is total reflection If some energy is transmitted and some is reflected, the wave is partially reflected
What is the Law of Reflection Angle of incidence = Angle of reflection In other words, light gets reflected from a surface at ____ _____ angle it hits it. The same !!!
What is the difference luminous and illuminous objects A luminous object is one that produces light. A illuminous object is one that reflects light. Luminous objectsIlluminous Objects
What are shadows? Shadows are places where light is “blocked” Rays of light
Light Summary 1)Light travels much faster than sound. 2)We see things because they reflect light into our eyes. 3)Shadows are formed when light is blocked by an object. 4)Light travels in a straight line. 5)Light is measured by its wavelength- unit =nanometer. 6)Light does not need a medium in order to travel. 7)Light refracts or reflects but does not absorb easily.