Visible irradiate is the part of the electromagnetic spectrum the our eyes can see:
It is just a small part of the complete spectrum, isn"t it?
Visible Spectrum
Visible Light: the wavelengths that are visible to most person eyes.
You are watching: Compared to yellow light, orange light has
The main colors, in order, go "Roy G Bv":Red Orange Yellow Green Blue Violet
As we see on this beautiful rainbow:
Wavelength
Light has actually a wavelength of about 380 nm to 750 nm, depending on color.
nm way nanometer, one billionth that a meter.
Example: red light has a wavelength of about 700 billionths that a meter (just less than one-millionth the a meter). Small!
THz method teraHertz, a sunshine cycles every second
So red light vibrates at around 400 million million cycles every second. Fast!
Higher frequency (with much shorter wavelength) has more energy:
Red light has actually lower frequency, much longer wavelength and also less energyBlue irradiate has higher frequency, shorter wavelength and an ext energy
Speed the Light
Light travel at practically 300,000,000 meters per second (to be exact: 299,792,458meters every second) in a vacuum.
That is 300 million meters every second, or:
3 × 108 m/s300,000 km/s186,000 miles per secondAt that rate light travels:
| 1 meter | in | 3.3 ns (3.3 billionths of a second) |
| Around the Earth"s equator | in | 134 multiple sclerosis (134 thousandths of a second) |
| From planet to Moon | in | 1.3 s |
| Surface of sun to Earth | in | about 8 minute |
It is therefore fast, yet still takes around 8 minutes from the surface ar of the sun to the Earth.
The symbol for this rate is c:
c ≈ 300,000,000 m/s
Light have the right to Travel Slower
We really shouldn"t call it the rate of light, firstly due to the fact that it uses to the totality electromagnetic spectrum, and gravity waves, and more. Possibly we could contact it "Max Speed"!
But likewise because light only travels that speed in a vacuum! It have the right to travel slower ...
Wavelengthand Frequency are Linked
The Wavelength and Frequency are related:
Frequency = VelocityWavelength
Wavelength = VelocityFrequency
Assuming the light is ina vacuum, the velocity is the rate of light:3 × 108 m/s
Let"s try a straightforward example (in this situation not a wavelength the light):
Imagine a really long wavelength of 75,000 km
Frequency = 300,000 km/s75,000 km
= 4 /s
= 4 Hz
We have the right to fit 4 the those wavelengths in 300,000 km, so it vibrates 4 times in 1 second.
So the frequency is 4 Hz (4 per second)
Or, the other method around, if we understand it vibrates 4 time a second we can calculate that wavelength:
Wavelength = 300,000 km/s4 /s
= 75,000 km
Example: Blue light has a wavelength of about 480 nm (480 × 10-9 m)
So the frequency is:
Frequency = 3 × 108 m/s480 × 10-9 m
= 6.25 × 1014 /s
= 6.25 × 1014 Hz
Which is 625 TeraHertz
Light travel in right Lines
Light travels in a straight line until its hits something, or it"s course is adjusted by different densities, or through gravity.
Wave
Light behaves together a wave, so the can:
scatter (bounce off in every directions),transmit (pass right through)or obtain absorbedPhotons
Light also behaves as packets that energy dubbed Photons.
We can measure a photon"s position and also momentum.Photons have no mass, however each photon has an quantity of energy based upon its frequency (number the vibrations per second)Each photon has a wavelengthSo it is like a particle and likewise like a wave. This is called the "wave-particle duality".
Einstein wrote:
"It appears as despite we need to use occasionally the one theory and also sometimes the other, when at time we may use either."
Intensity
Intensity is power every area, normally in watt per square meter:
Intensity = W/m2
Example: sun on a small 100 square meter house
About 150 come 300 watts of power are obtained from the sun per square meter.
Let"s pick the smaller number:
Intensity = 150 W/m2
How much Power is the over the entirety roof?
Power = 150 W/m2 × 100 m2
Power = 15,000 W
So a little house gets around 15 kilowatts top top it"s roof,which is several times an ext than a family members uses.
But that is just while the sun shines, and only about 20% deserve to be recorded by typical solar panels
But the is still too many of energy from the Sun.
Inverse Square
 | Inverse Square: when one value decreases together the square that the various other value. |
Example: light and also distance
The further away we are from a light, the much less bright it is.
The brightness decreases together the square of the distance. Because the light is dispersing out in all directions:
the power twice as far away is spread out over 4 times the areathe power 3 time as far away is spread out over 9 times the areaetcPolarization
Light is normally cost-free to vibrate in any type of direction at best angles to its path.
But polarized irradiate vibrates in one plane only:
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Polarizing lenses have the right to block irradiate from that plane, to cut down on reflect light and make it easier to see right into water:
Fiber Optics
Light, and infrared, have the right to be sent out along fiber optic cables, carrying information coded right into the wavelength.
The light continues to be inside since of a special building of refraction: when the refractive index is lower on the outside, and also the edge is not as well steep, the light beam has total internal reflection on the inside:
Fiber optic cables room much much better than electrical wires:
Wires get much more "noise" (other signals that distort or interfere through the original) from power lines, TV, radio, lightning etc.Photons have actually no mass so have the right to swap between 0 and 1 quickly. Electrons have mass and are slow in comparisonGlass has actually much much less resistance to light 보다 copper does to electrical signals, so deserve to go much more without needing a boost17760, 17763, 17764, 17766, 17767, 17761, 17762, 17765, 17768, 17769
Electromagnetic Spectrum Physics Index