So absorbance right here.

So let me do that in a different color.

So let's say there's some unknown concentration, and you figure out its absorbance is right over here.

So let me write down M for molar.

Here is another example of something which is this is a little spectrophotometer.

And you measure its absorbance, and you just get some number here.

let's say 0.2 molar.

So you measure its absorbance and you get its absorbance.

What I want to do in this video is to talk a little bit about spectrophotometry.

And over here you're measuring absorbance, in the vertical axis you measure absorbance.

The Beer Lambert law tells us that the absorbance is proportional

You could then measure for some unknown concentration.

If transmittance is a low number, that means you're absorbing a lot.

A higher number says your transmitting a lot.

So it's proportional to the path length times the concentration.

Light Speed

Black cloth absorbs light.

Black paper absorbs light.

It goes, I don't know, 0.1, 0.2, 0.3, so on and so forth.

This is actually a picture of the spectrum of the Sun.

So if transmittance is a large number, absorbance is a small number, which makes sense.

I'm sitting on a train.

AAVSO Light Curves...

There are these flashes

We use far red light, but even that's a problem because it gets absorbed so quickly.

If you're good at absorbing, that means you're not transmitting much.

The x ray absorption spectroscopist's periodic table

It cannot hide behind the black hole.

luminosity, top right.

If you're good at transmitting, that means you're bad at absorbing, you don't have a lot to absorb.

What's going on here?

Or another way to say it is that the absorbance is equal to some constant it's usually a lowercase epsilon like that and this is dependent on the solution, or the solute in question, what we actually have in here, and the temperature, and the pressure, and all of that.

The most fundamental is called the breathing loop.

And then I learned how to purge.

AAVSO Light Curve Generator

Light Curve produced by the American Amateur Variable Star Observers

That for any concentration, the absorbance is going to be on a line.

And they show central surface brightness versus radius in the top left.

My eyes were intent on the scene.

So hopefully that gives you the intuition behind spectrophotometry.

Headaches, sensitivity to light.

If you're transmitting a lot of light, the absorbance number's going to be very small, which means you are not absorbing that much.

So let's say I have some light here of some intensity.

Thermosalinographs, fluorometer, carbon analyzer...

Scientists also take advantage of the fact that babies will slow down their sucking when something interests them and resume their fast sucking when they get bored.