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

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

## Visible Spectrum

Visible Light: the wavelengths that space visible come most human being eyes.

You are watching: Which carries more energy red light or blue light

The key colors, in order, go "Roy G Bv":Red Orange Yellow Green Blue Violet As we see on this beautiful rainbow: ## Wavelength Light has a wavelength of about 380 nm come 750 nm, relying on color.

nm way nanometer, one billionth of a meter.

Example: red light has actually a wavelength of about 700 billionths that a meter (just much less than one-millionth the a meter). Small!

THz way teraHertz, a sunshine cycles per second

So red irradiate vibrates at about 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 irradiate has higher frequency, much shorter wavelength and an ext energy ## Speed of Light

Light travels at almost 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 second

At that rate light travels:

DistanceTime
1 meterin3.3 ns (3.3 billionths of a second)
Around the Earth"s equatorin134 multiple sclerosis (134 thousandths of a second)
From planet to Moonin1.3 s
Surface of sun to Earthinabout 8 minute

It is so fast, however still takes about 8 minutes from the surface of the sun to the Earth.

The symbol for this rate is c:

c ≈ 300,000,000 m/s

## Light can Travel Slower

We really shouldn"t contact it the speed of light, firstly due to the fact that it uses to the whole electromagnetic spectrum, and gravity waves, and more. Possibly we could call it "Max Speed"!

But likewise because light only travels that speed in a vacuum! It deserve to travel slower ...

The Wavelength and also Frequency space 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 situation not a wavelength of light):

### Imagine a really long wavelength of 75,000 km Frequency = 300,000 km/s75,000 km

= 4 /s

= 4 Hz

We deserve to fit 4 that those wavelengths in 300,000 km, so that 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 times a 2nd 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 travels in straight Lines

Light travels in a right line till its hits something, or it"s course is adjusted by different densities, or by gravity. Light native the sunlight streams across the road.The shadows likewise show the light travels in directly lines. This irradiate spreads out a little and is scattered by the atmosphere. Laser beams making straight lines. ## Wave

Light behaves as a wave, so that can:

scatter (bounce turn off in all directions),transmit (pass directly through)or gain absorbed

## Photons

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

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

So that is choose a particle and additionally like a wave. This is called the "wave-particle duality". Einstein wrote:

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

## Intensity

Intensity is power per area, usually in watt per square meter:

Intensity = W/m2

### Example: sun on a little 100 square meter house

About 150 to 300 watts of energy are obtained from the sun per square meter.

Let"s choose the smaller sized number:

Intensity = 150 W/m2

How much Power is the over the totality roof?

Power = 150 W/m2 × 100 m2

Power = 15,000 W

So a small house gets about 15 kilowatts top top it"s roof,which is several times more than a family uses.

But the is just while the sunlight shines, and also only about 20% deserve to be captured by usual solar panels

But that 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 more away we are from a light, the much less bright that is. The brightness decreases together the square of the distance. Since the irradiate is spreading out in every directions:

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

## Polarization

Light is normally free to vibrate in any direction at right angles to its path.

But polarized light vibrates in one aircraft only: Light gets partly polarized as soon as itbounces off surfaces prefer water or glass.

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Polarizing lenses can block light from that plane, to reduced down on reflect light and also make it much easier to see into water: Without and with a polarizing lens

## Fiber Optics

Light, and also infrared, have the right to be sent out along fiber optic cables, carrying info coded into the wavelength. Fiber optic cables

The light continues to be inside since of a special residential property of refraction: when the refractive table of contents is lower on the outside, and also the angle is not as well steep, the irradiate beam has complete internal reflection ~ above the inside: Light bounces turn off the wall surfaces inside the cable

Fiber optic cables room much far better than electric wires:

Wires get more "noise" (other signals that distort or interfere through the original) from power lines, TV, radio, lightning etc.Photons have no massive so have the right to swap between 0 and 1 quickly. Electrons have mass and are slow in comparisonGlass has much less resistance come light 보다 copper walk to electric signals, so have the right to go much more without needing a boost

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Electromagnetic Spectrum Physics Index