hey everybody it's dr. O'Neill let's get our learn on have you ever wondered why we have to use immersion oil you ever wondered why we have a oil immersion objective on a microscope so what's the oil all about well let's dive in so first before we can talk about that let's just a little bit of terminology reflection versus refraction so if let me go ahead and get my pen out here and let's say we have a medium here of any we'll say if the glass slide doesn't matter if light strikes it and bounces off of it then it's been reflected if as it travels through it it changes direction it's been refracted all right so we're going to be talking about the refraction of light here primarily so let me go ahead and get this cleaned off so big picture here's what happens what we'd like to happen is as light travels through the microscope towards the viewer which would be you we want to take a nice straight shot but doesn't work that way without a little help because it's because light rays can Bend they can really can refract so what happens is a lot of times the light starts to veer off to one side and I change the color there sorry about that and we'll go ahead and we'll look at that a little bit more closely here so we were just meant this is just the the idea behind the diff think about what a lens is actually as they've been created that's just it's a bunch of prisms and that leads to some refraction of light and it's generally not a big deal at the lower magnifications like scanning power low-power hydride power but when you to the higher magnification there's not that much light to go around so we can't afford to have a bunch of light rays bending and missing the objective nuts that's the whole point here so here as you see just again to reiterate what refraction is as light travels through a substance through a medium it's going to bend and we have to try to limit that and that is where immersion oil comes into play this is just a cool example of it this is actually a straight pole but it looks like it's bent because the refractive index of water is different than there in fact severe and that brings us to our point today so without immersion oil as light travels up make sure I have my red back here as light travels up towards you know through the through the glass slide through the specimen through air because there wouldn't be any oil there a lot of the light rays are going to bend or refract and they're going to actually miss the objective and then I can do any good so the reason you had an immersion oil is because immersion L which is really nothing fancy it's basically mineral oil has the same refractive index as glass so as far as the light is concerned it actually has not stopped traveling through the slide so more light rays are gonna travel up into the one haired X objective towards the 10x or whatever magnification ocular you have and you're going to get a nice clean image so you can try to use oil immersion objectives without oil but it's generally going to be very fuzzy mess so the immersion oil speaking of messes that can be very messy to work with but it really is a game-changer at these higher magnifications alright I hope that helped you understand this concept and have a wonderful day go change the world you