What is it and how does it work a type of electromagnetic radiation of a specific wavelength Some of these wavelengths we can see visible light Some wavelengths we cannot see xrays infrared ultraviolet ID: 502129
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Light
What is it and how does it workSlide2
a type of electromagnetic radiation of a specific wavelengthSome of these wavelengths we can see (visible light) Some wavelengths we cannot see (x-rays, infrared, ultraviolet)Light isSlide3
Light has characteristics of both waves and particlesAs a wave: light has an amplitude, frequency and wavelength. Light waves can also interfere with one another. Light can reflect, refract and diffract just like other waves doLight can be described as a particle and a waveSlide4
Light has characteristics of both waves and particlesAs a particle: light bounces off surfaces in random directions like particles would doThe particles of light are called photonsLight can be described as a particle and a waveSlide5
Light scatters its energy as it moves away from its energy source
Light scatters in all directions and fills up space. That’s why a whole room can be lit up with on lightWhy is the sky blue? Blue light has the shortest wavelength and scatters more than other light
Properties of lightSlide6
The brightness of light depends on the light’s intensity Intensity decreases and distance increases Light IntensitySlide7
Light has a speed of 3 X 108 m/s (186,000 m/s)Light will slow down as it passes through air, water, and glassThe speed of light depends on the medium
material
n
material
n
Vacuum
1
Crown Glass
1.52
Air
1.0003
Salt
1.54
Water
1.33
Asphalt
1.635
Ethyl Alcohol
1.36
Heavy Flint Glass
1.65
Fused Quartz
1.4585
Diamond
2.42
Whale Oil
1.460
Lead
2.6Slide8
More energy = higher frequencyLess energy = lower frequencyThe energy of light is proportional to its frequencySlide9
EM spectrum consists of all energies, wavelengths, and frequencies of light.The Electromagnetic SpectrumSlide10
Waves on the EM spectrum that we can see is called visible light Red, orange, yellow, green, blue, indigo, violet (ROYGBIV)But there are lots of waves on the spectrum we cannot see like radio waves, infrared waves, x-rays, etc.The Electromagnetic SpectrumSlide11
When light hits a surface, it will bounce off at the same angle it hit the surface at.Smooth surfaces – light rays bounce in the same directionRough surfaces – light rays bounce off in many directions
Some light is reflected by an object and some light is absorbed Slide12
Remember from the wave unit that when light bounces off an object, it is known as reflectionReflection Slide13
When light is absorbed by an object, the energy from the light is transformed into heat energyThat’s why you feel warm when you’re outside in the sun. Your body is absorbing the light energy and changing it into heat!Some light is reflected by an object and some light is absorbed Slide14
The color you see depends in the wavelength of light that reaches your eyesshorter wavelength = purple/blue = higher frequencylonger wavelength = red/orange = lower frequency
Why do we see colors?Slide15
The light from the sun contains all the wavelengths of the colors we seeWhen the white light strikes an object all the colors are absorbed by that object except for the color we see. That color is reflected into our eyesWhy do we see colors?Slide16
Most colors are a mixture of more than one wavelength (color)
Primary colors – red, yellow, blue, mix together to produce all the colors we can see
When all the colors of light combine we see white
Black is the absence of light
Why do we see colors?Slide17
Remember when light enters a new medium like air, water, or glass, the wave will bend.This is called refractionThis is because the light slows down as is passes through different mediumsRefraction makes objects appear like they are in different positions
Refraction Slide18
When light hits a lens (like in your eye) the wave will change directionConvex Lenses- like in your eye- turn images upside downConcave LensesLensesSlide19
Rainbows- how to they work?
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