LIGHT WAVES Subtitle What is Light Light is

LIGHT WAVES Subtitle

What is Light? § Light is a type of energy that travels as waves. § Thing like a candle or fish that live in the ocean produce light. § Compared to other types of waves, light waves are different. For example, sound waves must travel through matter, while light waves don’t. § For that reason, light is an electromagnetic wave.

Electromagnetic Waves § Electromagnetic waves have 2 parts. These 2 parts are made up of changing electric and magnetic fields. § When an electrically charged particle vibrates, it disturbs the electric and magnetic fields around it. And by that happening, these 2 vibrating fields produce electromagnetic waves (EM) § These fields are perpendicular to each other and carry away the charged particle, and because they exist an empty space, they don’t need a medium in which to travel.

Electromagnetic Spectrum § When looking around you, light reflects in you eyes. Light that we already see is called visible light § But if a bee was in the room, it would be seeing another type of light, in which we call ultraviolet light (that you cant see) § Both of these types of light are part of larger range of waves called the electromagnetic spectrum § The EM spectrum is composed of different types of waves which include x-rays, microwaves, and radio waves, all in which have different frequencies.

Speed of Light § In a vacuum, all EM waves, including light, move at the same speed which is 300, 000 m/s. § This is called the speed of light, which is constant (will form a straight line in a graph) § And although EM waves don’t need a medium to travel to, they can travel through many other materials § When they do, they travel more slowly than they do in a vacuum.

Energy and Frequency § EM waves depend on the wave’s energy to determine which energy it should use. § High-frequency, short-wavelength EM waves have more energy than lowfrequency, long-wavelength waves. § The more energy EM waves have, the more dangerous they can be.

Light Waves and Color § Light waves are usually invisible for us because their wave lengths are either too short or too long for our eyes to see § However, when we do see visible light that have wavelengths that appeal to our sight, we see such a thing called color. § Depending on the wavelength and the frequency of the light, we could see different colors

Light Waves and Color § White light is what we perceive when our eyes detect all wavelengths of visible light at once in equal proportions § And as we said, The wavelength and frequency of light usually determines its color. § The shortest wavelengths of light are seen as violet, while the longest wavelengths are seen as red. § Fun Fact: The night sky is actually red, but because there isn’t a good source of light and the red wavelengths aren’t visible, we see it as black.

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