Ultraviolet investigations for GCSE Physics #physics #gcsephysics

Added: 2026-05-22

[00:00:01]Hi there.

[00:00:02]Today we're going to look at ultraviolet. I've got an ultraviolet photo detector here. We've got an ultraviolet LED here. You can you can just about see it in the roof of the housing there.

[00:00:12]And kit from Lascells, both of these.

[00:00:15]And we're going to see what can stop ultraviolet essentially. So, if I set this up carefully so it's in the right place.

[00:00:25]Switch it on. We'll measure a little bit of voltage maybe. Oh, no, no, it doesn't look as if it's going to um I thought it might do because there's a little bit of natural light in the room.

[00:00:34]If we switch on the LED, you can see that the voltage there goes up to about 4 volts, 4 and 1/2 volts, okay?

[00:00:41]I've only got 8 9 volts. I could maybe raise that a little bit up to 10 volts.

[00:00:47]So, try and get it to be around 5 volts on this multimeter here. Now, there's various things you could look at here. So, for example, you could look at filters, okay? So, you could put in various colored filters in and see what happens in terms of UV. So, if I put this purple one in position, it's gone from 5 volts way down, okay, down to 2 volts there, okay?

[00:01:13]In contrast, if I try a blue filter, it will go down to 1.2 volts, okay?

[00:01:24]Um and if I try something like a red filter the other end of the spectrum, then you can see that that completely blocks it, as we'd expect.

[00:01:35]It's not just that you can look at you could look at glass as well. So, I've just got some um slides here.

[00:01:41]So, you see how much the level of glass how much glass you need to reduce the UV going through it. So, it's gone down a little bit there, okay, with one.

[00:01:51]Two there, a bit more. I'm going to add two at the same time here.

[00:01:55]So, you've got four slides in. That's gone down quite appreciably, but that's quite a thick bit of glass there, okay?

[00:02:01]Um let's move that back again.

[00:02:04]And let's try a final thing. We could try fabrics, okay? Which fabrics are good at blocking ultraviolet? So, let's try a bit of plastic here, okay?

[00:02:14]See-through plastic. See if we can fit it in the gap. There you go.

[00:02:18]So, that's gone down quite a bit from nearly five down to three volts.

[00:02:23]And let's try a bit of white fabric.

[00:02:28]There you go. That's gone down to two.

[00:02:30]Well, it's gone down to 0.2, okay? So, it's blocked most of it, okay?

[00:02:34]And let's try now a bit of dark fabric.

[00:02:36]Try and get a single layer.

[00:02:40]There we go. And the dark fabric goes down to 0.1. So, probably the best of those that I've tried there so far.

[00:02:47]So, there's loads of investigations you can do. Ultraviolet's obviously in the curriculum at GCSE uh electromagnetic spectrum. And it just brings it to life a little bit, I think.

[00:02:56]Good set of kit there from Lascells.