Visible light is the part of the electromagnetic spectrum that our eyes deserve to see:

It is only a small component of the complete spectrum, isn"t it?

Visible Spectrum

Visible Light: the wavelength that room visible to most human being eyes.

You are watching: Which color light has the highest energy

The main colors, in order, walk "Roy G Bv":Red Orange Yellow Green Blue Violet


As we view on this beautiful rainbow:




Light has actually a wavelength of around 380 nm come 750 nm, depending upon color.

nm method nanometer, one billionth of 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 sunshine cycles every second

So red light vibrates at around 400 million million cycles every second. Fast!

Higher frequency (with much shorter wavelength) has an ext energy:

Red light has actually lower frequency, much longer wavelength and less energyBlue light has higher frequency, shorter wavelength and much more energy


Speed that Light

Light travels at virtually 300,000,000 meters every second (to it is in 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 second

At that speed light travels:

1 meterin3.3 ns (3.3 billionths that a second)
Around the Earth"s equatorin134 ms (134 thousandths the a second)
From earth to Moonin1.3 s
Surface of sun to Earthinabout 8 minutes

It is so fast, yet still takes around 8 minute from the surface of the sunlight to the Earth.

The symbol for this rate is c:

c ≈ 300,000,000 m/s

Light deserve to Travel Slower

We really shouldn"t contact it the rate of light, firstly due to the fact that it applies to the entirety electromagnetic spectrum, and gravity waves, and more. Maybe we could call it "Max Speed"!

But likewise because light only travels that rate in a vacuum! It have the right to travel slow ...

Wavelengthand Frequency room Linked

The Wavelength and Frequency room 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 an easy example (in this case not a wavelength of light):

Imagine a very long wavelength of 75,000 km


Frequency = 300,000 km/s75,000 km

= 4 /s

= 4 Hz

We have the right to fit 4 that those wavelengths in 300,000 km, so the vibrates 4 times in 1 second.

So the frequency is 4 Hz (4 every second)

Or, the other method around, if we know it vibrates 4 times a 2nd we can calculate its 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 travel in straight Lines

Light travels in a directly line until its hits something, or it"s route is changed by various densities, or by gravity.

Light native the sun streams across the road.The shadows also show that light travels in directly lines.

This irradiate spreads the end a little and is scattered by the atmosphere.

Laser beams making directly lines.



Light behaves as a wave, so the can:

scatter (bounce off in every directions),transmit (pass right through)or acquire absorbed


Light also behaves as packets the energy referred to as Photons.

We can measure a photon"s position and momentum.Photons have actually no mass, however each photon has actually an amount of energy based on its frequency (number the vibrations per second)Each photon has actually a wavelength

So it is prefer a particle and also like a wave. This is referred to as the "wave-particle duality".


Einstein wrote:

"It appears as though we need to use periodically the one theory and sometimes the other, while at times we might use either."


Intensity is power per area, normally in watts per square meter:

Intensity = W/m2

Example: sun on a tiny 100 square meter house

About 150 come 300 watts of power are got from the sun per square meter.

Let"s choose the smaller sized number:

Intensity = 150 W/m2

How lot Power is that over the whole roof?

Power = 150 W/m2 × 100 m2

Power = 15,000 W

So a little house gets about 15 kilowatts ~ above it"s roof,which is several times much more than a family uses.

But the is just while the sun shines, and only about 20% can be caught by common solar panels

But the is still lots of energy from the Sun.

Inverse Square

Inverse Square: when one worth decreases together the square that the other value.

Example: light and distance

The additional away we are from a light, the much less bright that is.


The brightness decreases as the square the the distance. Due to the fact that the light is dispersing out in every directions:

the power twice as much away is spread over 4 times the areathe power 3 time as far away is spread over 9 time the areaetc


Light is normally free to vibrate in any type of direction at best angles come its path.

But polarized irradiate vibrates in one plane only:

Light gets partly polarized when itbounces off surfaces prefer water or glass.

See more: How Many Seconds In 2 Years To Seconds Conversion (Yr To Sec)

Polarizing lenses have the right to block irradiate from the plane, to reduced down on reflect light and also make it less complicated to see right into water:

Without and with a polarizing lens

Fiber Optics

Light, and infrared, can be sent along fiber optic cables, carrying details coded right into the wavelength.

Fiber optic cables

The light remains inside since of a special property of refraction: when the refractive index is reduced on the outside, and also the edge is not as well steep, the light beam has full internal reflection top top the inside:

Light bounces turn off the wall surfaces inside the cable

Fiber optic cables are much better than electric wires:

Wires get an ext "noise" (other signals the distort or interfere v the original) from power lines, TV, radio, lightning etc.Photons have no mass so have the right to swap in between 0 and 1 quickly. Electrons have mass and are slow-moving in comparisonGlass has actually much less resistance to light 보다 copper does to electrical signals, so deserve to go much additional without needing a boost

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