Interesting example of Aliasing

Okay, I stuck a moment without the kids to do this for you. I'm going to show you a principle called aliasing. Aliasing is when your sample rate of your measuring device is not fast enough to actually catch the true frequency of what's happening, so you can get a false reading.

So here, there's a string, and we can turn this string on so that it rotates. Got a rotating wheel here, and here we have a stroboscope invented by Dr. Edgerton. So, we will turn the stroboscope until you can actually stop the rotation of this string. So, here it looks like the string is rotating at about 1 Hertz, or maybe more like half a Hertz, but in actuality, it's rotating much, much faster than that—something like 40 or 50.

So, the sample rate of the stroboscope, or the time at which you're taking a measurement, is not fast enough to get the true value. There you go! So here, the sample rate appears to be very, very… or the measured value seems to be very, very low. Yep, that's it!

So, once we turn up our measurement frequency, you can see that it starts to become more apparent that it's rotating, and you can actually get another false measurement here. It looks like there are several strings, which is not the case.

So, all right, that's it! Daddy's had his science fun; now I got to go find the kids. Okay, they're studying rotational inertia. Dad, I want to go and make some slime!

You want to make some slime? I want to go and get some slime. Slime? You want SL with me?