Name: 黄色い街灯 - 60のシンボル (Yellow Street Lights - Sixty Symbols)
Uploaded: 2021-01-14T10:32:01.000Z
Duration: 9 min 21 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

程度の副詞

So now, Brady, if you put those on your camera, If you look through a white light source, you're going to see a really dramatic effect.

We're talking about why I can't tell my rubbish bins apart when I go out the night before to put them to the curb.

You have multiple bins that are due to be put out on different dates.

You have to keep track of when the recycling goes out.

When the normal rubbish goes out and here, not in him.

In my case, one is green, one is black, one is brown, and often when you go out at night, you can't actually tell them apart.

And that's because much of the illumination that we get now from streetlights comes from a certain kind of lamp called sodium lamp.

That is changing, however, certainly here not am around the country and probably in place around the world.

There's a big drive towards replacing those sodium bulbs by led light light emitting diodes, which give a very different kind of light.

So today we're gonna talk about why, under sodium lamps.

This is a light source that is emitting light at only a single particular wavelength, 589 nanometers.

And that corresponds to a very yellow orange light, as you can see, because that's the wavelength of yellow in the optical spectrum.

So there's a tube in here in which atoms of sodium are being excited.

The electrons are jumping up to high energy levels.

When they fall down, they emit a certain wavelength of light, corresponding to the energy difference between those energy levels.

Well, the question is, why do we see color, asshole?

If we're outside in the daytime and our only source of illumination is the sun, then the son we know emits light at all wavelengths and together that makes a very white ish light.

It doesn't emit light exactly the same amount at each wavelength, but overall it covers the whole spectrum.

However, when we have an artificial source of light, we're not always going to get that full spectrum wavelength coverage.

And here's a really extreme case of that, so we don't have white light at all.

So when we have white light, it may hit objects.

Some of that light will be absorbed, some will be transmitted and some will be reflected.

It's on Lee the light that's reflected back to us that gives an object of color.

So in the case of white light, all of those wavelengths are provided, and only some of them, you know, bounce back to us if you don't have that full spectrum to begin with, If you're only bouncing light of a certain color off your object, you're not going to be able to distinguish.

What is true color is so these air really fun.

These air diffraction glasses and so etched in very, very fine find much more finding you could actually see our little grooves etched into the plastic.

And what happens when the light passes through?

Those is its defected, so it spreads out like a prison will spread out white light, and it lets you see the whole rainbow of color.

So, Brady, if you put the glasses over your camera and you look at a white light source, you should see a pretty spectacular effect.

With that white light being spread out across all wavelengths in the spectrum.

So now you're seeing what is making up all that white light.

But if you then look at our sodium lamp, you're not gonna get that same effect.

Of course, there isn't that wide wavelength range to begin with.

To spread out, you should only see another image of the same lamp because that's all you have to defect.

So for comparison, here's the white light, and then you can have a look at the sodium lamp and see the difference.

Okay, so let's go into the white light here.

So here we have a fluorescent light emitting wavelengths from the blue to the red, which gives it a white appearance overall.

So we've got our our our pain as well in the vending machine, right?

So we've got the full rainbow here under the white light.

You know, the white light's bouncing off.

The blue light is bouncing off these ones.

The yellow light's bouncing off these ones.

However, we take them back to our sodium lamp.

We're going to see something very different flowing into the boat.

I mean, you can still tell which ones are light and which ones are dark.

You've lost the ability to distinguish what color it is.

You can probably take a pretty good educated guess that that is yellow or orange, because it's matching the color of that life.

But beyond that, I think you'd be hard pressed to determine which one is blue.

So we've got some crayons here, but I don't think similarly you would be able Thio, tell apart which ones these are.

Do you wantto do to be calmer camerawoman?

I want you to take those crowns and write down what you think.

I mean, I think they're all brown, but right, Brown for all of them.

Okay, so you got the yellow right, But then you did it again and thought it was orange on.

But I don't think you got anything else right?

Causes yellow light eso Imagine a city where this is the only light source available at night when these air what the street lights look like in reality around here.

That's not quite the case because thes sodium lights, we have our high pressure sodium lights.

So while there intensely orange, they're not single wavelengths like this.

It gives it a bit of coverage in the in the blue and the violet.

San Jose in California is one of them that uses or has used low pressure sodium lights completely to illuminate the city.

The reason San Jose did this is there's actually an astronomical observatory lick observatory on Mount Hamilton.

So in the interests of helping the astronomers maintain the purity of the night sky, they legislated that they would use low pressure sodium lights on, and so they produce a light that's easily blocked out by filters.

For the astronomers, it makes everyday life for every night life very challenging because he can't distinguish colors.