[Music] in this video we're going to look at microscopy which just refers to the use of microscopes so we'll cover how light microscopes work and then explain what the terms object image magnification and resolution mean let's start though by looking at the different parts of a light microscope supporting the entire thing is the base at the bottom and then the arm that connects the bottom to the top then we have some kind of light source which on some microscopes will be a lamp but in this case it's just a mirror that will reflect the light from the room and just above it is the stage which is where we put our microscope slide then in the top half we have all of our lenses so we normally have three objective lenses which we can choose between and each have different magnifications like perhaps 10 times 20 times and 50 times magnifications and then we also have an eyepiece lens which has a fixed magnification and sits at the top where we look into the microscope then the last things to notice are the body tube just here and finally the coarse and fine focusing knobs which we can turn to help us get the image in focus now before we go any further we need to introduce the terms object and image in microscopy the term object refers to the real object or sample that you're looking at so if we had some onion cells on our microscope slide then the onion cells themselves would be the object the term image on the other hand refers to the image that we see when we look down the microscope for example if we were to look down this microscope we might see something like this so this would be our image of the onion cells whereas the object is the actual onion cells that are sitting there on the microscope slide so just be really careful not to get these two terms confused if we move on to how they work light from the room is going to hit this mirror here and be reflected upwards through the object that we want to look at in this case through our onion cells which remember us sitting there on the stage then we'll pass through one of the objective lenses then through the eyepiece lens and finally into our eye we should be looking into the eyepiece and the idea of this whole thing is that the lenses will spread out the light rays so that the image that we see is far larger than the actual object this brings us nicely to our next term you need to know magnification which we can define as how many times larger the image is than the object so if the image appeared 1000 times larger than the object then the magnification would be times one thousand there's also an equation for magnification which says that magnification is equal to image size divided by object size and we're going to take a look at how to use it in another video the final term you need to know is resolution which we can define as the shortest distance between two points on an object that can still be distinguished as two separate entities now i know that this is kind of a complicated definition but it basically means the shortest distance that two parts of an object can be apart without appearing blurred or in other words it's a measure of how detailed the image is for example if we look at these two images of the onion cells from earlier we can see that they both have the same magnification because they both have times 100 in the bottom corner and the cells in each image both look the same size however the one on the right looks much blurrier and this is because it has a lower resolution so we can't see the same level of detail so in general just remember that the higher the resolution of an image the more details you'll be able to see and the less blurry it will look anyway that's everything for this video so if you want to practice questions on this then just check out the link in the top right corner of this screen or in the pinned comment down below and hopefully we'll see you next time