Visible light is the part of the electromagnetic spectrum the our eyes deserve to see:
It is just a small component of the full spectrum, isn"t it?
Visible Spectrum
Visible Light: the wavelengths that room visible come most human being eyes.
You are watching: Because violet light has more energy than red light,
The key colors, in order, walk "Roy G Bv":Red Orange Yellow Green Blue Violet
As we check out on this beautiful rainbow:
Wavelength
Light has actually a wavelength of around 380 nm to 750 nm, depending upon color.
nm method nanometer, one billionth that a meter.
Example: red light has a wavelength of around 700 billionths the a meter (just much less than one-millionth the a meter). Small!
THz way teraHertz, a trillion cycles per second
So red irradiate vibrates at about 400 million million cycles every second. Fast!
Higher frequency (with shorter wavelength) has more energy:
Red light has actually lower frequency, much longer wavelength and also less energyBlue light has greater frequency, shorter wavelength and an ext energy
Speed the Light
Light travels at virtually 300,000,000 meters every second (to be exact: 299,792,458meters per second) in a vacuum.
That is 300 million meters every second, or:
3 × 108 m/s300,000 km/s186,000 miles every secondAt that rate light travels:
| 1 meter | in | 3.3 ns (3.3 billionths of a second) |
| Around the Earth"s equator | in | 134 ms (134 thousandths that a second) |
| From earth to Moon | in | 1.3 s |
| Surface of sunlight to Earth | in | about 8 minutes |
It is for this reason fast, however still takes around 8 minute from the surface ar of the sun to the Earth.
The symbol because that this rate is c:
c ≈ 300,000,000 m/s
Light can Travel Slower
We yes, really shouldn"t call it the speed of light, firstly due to the fact that it applies to the entirety electromagnetic spectrum, and gravity waves, and more. Maybe we could contact it "Max Speed"!
But likewise because irradiate only travel that rate in a vacuum! It deserve to travel slower ...
Wavelengthand Frequency space Linked
The Wavelength and Frequency are related:
Frequency = VelocityWavelength
Wavelength = VelocityFrequency
Assuming the irradiate is ina vacuum, the velocity is the speed of light:3 × 108 m/s
Let"s try a an easy example (in this situation not a wavelength that light):
Imagine a very long wavelength that 75,000 km
Frequency = 300,000 km/s75,000 km
= 4 /s
= 4 Hz
We have the right to fit 4 of those wavelength in 300,000 km, so the vibrates 4 times in 1 second.
So the frequency is 4 Hz (4 every second)
Or, the other way around, if we recognize it vibrates 4 time a 2nd we have the right to calculate that wavelength:
Wavelength = 300,000 km/s4 /s
= 75,000 km
Example: Blue light has actually 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 travels in right Lines
Light travels in a right line till its hits something, or it"s path is readjusted by different densities, or through gravity.
Wave
Light behaves together a wave, so the can:
scatter (bounce off in every directions),transmit (pass straight through)or obtain absorbedPhotons
Light also behaves together packets that energy dubbed Photons.
We have the right to measure a photon"s position and also momentum.Photons have no mass, however each photon has an amount of energy based upon its frequency (number of vibrations per second)Each photon has actually a wavelengthSo the is favor a particle and additionally like a wave. This is referred to as the "wave-particle duality".
Einstein wrote:
"It appears as despite we have to use occasionally the one theory and sometimes the other, if at time we may use either."
Intensity
Intensity is power every area, generally in watts per square meter:
Intensity = W/m2
Example: sun on a small 100 square meter house
About 150 come 300 watts of power are received from the sunlight per square meter.
Let"s choose the smaller number:
Intensity = 150 W/m2
How lot Power is the over the entirety roof?
Power = 150 W/m2 × 100 m2
Power = 15,000 W
So a small house gets around 15 kilowatts top top it"s roof,which is several times much more than a family members uses.
But the is just while the sunlight shines, and only about 20% have the right to be caught by typical solar panels
But the is still lots of power from the Sun.
Inverse Square
 | Inverse Square: when one worth decreases together the square the the various other value. |
Example: light and also distance
The more away we are from a light, the much less bright it is.
The brightness decreases together the square the the distance. Due to the fact that the light is spreading out in every directions:
the energy twice as far away is spread over 4 time the areathe power 3 times as far away is spread over 9 time the areaetcPolarization
Light is normally complimentary to vibrate in any type of direction at ideal angles to its path.
But polarized irradiate vibrates in one aircraft only:
See more: How Many Cm In 22 Inches To Cm, 22 Inches To Cm
Polarizing lenses can block irradiate from the plane, to reduced down on reflected light and also make it much easier to see into water:
Fiber Optics
Light, and also infrared, deserve to be sent out along fiber optic cables, carrying info coded into the wavelength.
The light continues to be inside due to the fact that of a special residential property of refraction: when the refractive table of contents is reduced on the outside, and the edge is not as well steep, the irradiate beam has total internal reflection ~ above the inside:
Fiber optic cables are much much better than electrical wires:
Wires get much more "noise" (other signals that distort or interfere through the original) from strength lines, TV, radio, lightning etc.Photons have no fixed so can swap between 0 and also 1 quickly. Electrons have mass and are slow in comparisonGlass has actually much less resistance come light than copper walk to electrical signals, so can go much further without needing a boost17760, 17763, 17764, 17766, 17767, 17761, 17762, 17765, 17768, 17769
Electromagnetic Spectrum Physics Index