# Properties of Light

by Jared Rovny

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00:02 Now that we've introduced the basics of light.

00:04 We're ready to discuss some of the properties of light including polarization, as well as the electromagnetic property of light as a wave.

00:13 Since we've already discussed the basic wave phenomenon.

00:16 After this lecture we'll talk about the light spectrum in a little more detail.

00:20 But first, we'll start with the properties of electromagnetic radiation.

00:24 Going into radiation, the way we describe light is with an oscillating electric and magnetic field as you can see here.

00:31 As we discussed, an electric field that's changing, creates a magnetic field and vice versa.

00:38 And so a light ray like this one that you see here with a particular wavelength has both an electric field component and a magnetic field component and these two are mutually propagating as the light wave moves through space.

00:52 We can determine the direction of this light wave by again using the right-hand rule which we saw ourselves using a few times already before.

00:59 In this case, you would put your fingers in the direction of the electric field and then curl those fingers or point your palm in the direction of the magnetic field.

01:08 In this case, you can see by putting your fingers up, pointing your palm downwards.

01:11 We can see that the light ray in this case will be pointing out of the page more towards us.

01:16 The velocity of the light is something that we've brought up briefly already.

01:20 And it is approximately three times 10 to the eighth meters per second, which is obviously very, very fast.

01:27 We should be aware that this number is slightly rounded it turns out that the real number is more like 2.9979 which is also obviously very close to three and so there's not much difference between this number and the actual number.

01:42 And this is the one used in the literature quite often especially when you're trying to solve problems.

01:47 The velocity is fixed for light which we know because we discussed that the velocity of a wave is fixed by a given medium.

01:56 So if we know this fixed constant velocity of light which is always the velocity of light.

02:01 Then we can always find the wavelength or the frequency of light if we know one or the other just by using our wave velocity equation which we have written on the bottom here.

02:10 And be aware of course that in the wave velocity equation as it is written here.

02:14 The velocity of light will just be this c value that we've just introduced.

### About the Lecture

The lecture Properties of Light by Jared Rovny is from the course Light: Electromagnetic Radiation.

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