Introduction to Light
description
Transcript of Introduction to Light
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Introduction to Light
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What is light ?
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Light is electromagnetic radiation of a specific
wavelength and frequency that is detectable by the
human eye.
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What is a wavelength?
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A wavelength is the distance between the points where a
wave repeats itself.
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Electromagnetic radiation, Light wave.
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Wavelength
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Wavelength
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Wavelength
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Wavelength Wavelength Wavelength
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Light has a wavelength of between 380 and 740 Nanometres.
That’s 0.000038 cm and 0.000074 cm
A human hair is approximately 0.007 cm thick
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That means, you will need over 18,000 wavelengths of light to make one centimetre or 140 wavelengths to
cross a single hair.
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What is frequency ?
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Frequency is the number of wavelengths that pass in a unit of time, which in this
case is one second.We call this unit of
measurement Hertz.
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1 Second
1 2 3 4 5 6 7 8 99 Hertz
(9 wavelengths per second)
Frequency
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1 Second
1 2 3 4 5 6 7 8 99 Hertz
(9 wavelengths per second)
Frequency
1 2 3 44 Hertz
(4 wavelengths per second)
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What is amplitude ?
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Amplitude is the height of the wave.
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Amplitude
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Physics has a great deal of trouble explaining the intensity or strength of light using waves. This is where the deal theory of light as a particle takes effect. The intensity of light is easily explained but considering a larger
number of photons being produced and reaching your eye creates a “brighter”
sensation.
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Different substances such as air or water, block different wavelengths and
frequencies of electromagnetic radiation.
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Air and it’s effect on solar radiation.
Surface of the Earth
Height.
Image: Courtesy NASA/JPL-Caltech
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How do we draw light in science diagrams?
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Light travels in a straight path, so we represent it using a single line or ray, with an
arrow at the end showing the direction the light is travelling.
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Light travels in a straight path, so we represent it using a single line or ray, with an
arrow at the end showing the direction the light is travelling.
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Light on earth can be reflected or refracted but cannot be
curved or bent.
Reflection
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Light on earth can be reflected or refracted but cannot be
curved or bent.
Refraction
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Light on earth can be reflected or refracted but cannot be
curved or bent.
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Whenever you are drawing a light ray, use your ruler to
make sure your line is straight.
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Now it’s your turn to draw some light rays from a source
to an eye.