Okay, So for this question, with us to find the waving light both within a vacuum on the material and there's traveling through this is first I'm just gonna write down following former C to be equal to London UK is everyone should know this form very well. At this point, I'm and say the first part question it's in a vacuum. So you don't need to consider is gonna be one on no effect. So here was simply gonna write a steal of light, and we're told that it's 5.8 10 40 hurts that. Remember that frequency? Okay, you take this in. Fine. We get 517 Another meeting. Okay. Now the next. I am part of questions. You want to find this wavelength when it's traveling through the material, which in the states block of glass. Okay, Now you see the previous question that I've done a video. We did a quick derivation of this formula, but it's fairly self explanatory. So again, and this just says that the effective index of one material multiplied by the waving like is equal to their refractive index In another material times the way like in that material okay, we know that the first interview the vaccine, that's gonna be one. Forget that. What we're trying to find is this. Okay, Say we re arrange this. We find that London to London gonna be two original wave, then divided by refractive index of that glass, which we're told is a 1.52 So we're gonna get five 17 instead, my nine animated there, Okay? And we just divide that three, but, um, 1.5. Okay. And we find that we're gonna get 340 that make it point full clams. Morning, Stephan.