Magnification, Resolution, & Contrast - Video Tutorials & Practice Problems
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Magnification, Resolution, & Contrast
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in this video we're going to define and distinguish between three terms that are very important when it comes to microscopy. And those three terms are magnification resolution and contrast and so effective. Microscopy actually requires a nice balance of the following three terms that we have numbered down below 12 and three. And those three terms. Once again our magnification resolution and contrast and notice that we have images down below for each of those terms. Now, the very first term that we have here is magnification, which most students have a general idea of what magnification is referring to. And so magnification is referring to the apparent increase in the size of an image through the use of these specialized objects known as lenses. And so the lenses will help to magnify the object and the higher the magnification is the larger the apparent size of the image. And so if we take a look at our image down below here for magnification, notice that on the left hand side over here we're showing you a snowflake viewed under a microscope at 93 X. Magnification. Which just means that the apparent size of the image is times larger than the actual size of the image. And so this snowflake that you see here in this image is appearing 93 times larger than the actual size of the snowflake. And so notice on the right hand side over here we're showing you the same exact snowflake just viewed at a much higher magnification, 908 X. Magnification versus the 93 X. Magnification on the left. And so this 908 X. magnification just means that the apparent size of the image is 908 times larger than the actual size of the object. And so really it's just zooming into this little circular blue region. And so that is what the right side is zooming into. And so it's basically magnification is almost like zooming in and being able to increase the apparent size of the image. Now, magnification is very important when it comes to microscopy. However, sometimes students mistakenly believe that magnification is the most important thing when it comes to microscopy. However, that's not always the case because resolution and contrast are equally as important as magnification. And so resolution is referring to the minimum distance that two objects must be in order to actually observe those two objects as being separate from one another. And so there's an associated term called resolving Power. That's associated with resolution. And resolving power is a measure of the ability to distinguish two separate objects that are very close together. And so sometimes if there's very, very poor resolution, then two objects that are really, really close may appear as a single object and so that would be really poor resolution. However, if you have really, really high resolution and high resolving power, then in that case two objects that are really, really close together can still be determined as separate. So let's take a look at our image down below to get a better understanding of resolution. And so this is showing you some algae viewed under a microscope. Now on the left hand side over here, What we have is really, really low resolution or really, really poor resolution. And so notice that these objects are all really, really close together, but you may mistakenly confuse them as being a single object here even though they are separate from one another. However, with a higher resolution and a higher resolving power, it's a lot more clear to see that these are actually separate entities and that they are actually separate from one another. Now notice that the magnification is equivalent across these two images, they have exactly the same magnification. What is different is not the magnification, it's the resolution. That is different. Which once again is that ability to be able to distinguish two objects that are really close together and identified them as being separate. So you can almost think of resolution as adding a pair of glasses to help make the image appear more clear and more crisp. And so that's why we've got the little pair of sun, uh not sunglasses, eyeglasses right there. Okay. And so the third and final term that we're going to talk about here in this video is contrast, which once again is equally as important as a resolution and magnification. And so contrast is referring to the difference in color or light intensity between an object and its immediate background. And so basically it's how well an object stands out from its background. And so this is going to help determine how easily cells and cell structures can be seen. And so if we take a look at our image down below for contrast, uh notice on the left hand side, we're showing you really, really low contrast are really, really poor contrast where the object that we're trying to visualize uh is a similar color and similar light intensity to the background. And so it makes a lot harder to be able to actually visualize these structures that are being shown here because the object does not stand out very well from its background. However, on the right over here, what we're showing you is a much higher contrast, a much greater contrast. And so what you can see is that the objects that are being visualized are much much easier to visualize because the color and the light intensity are very different between the object and its background. And so we have a very light object surrounded by a very dark background and that makes it a lot easier to be able to visualize. And so effective magnification once again requires a nice balance between magnification. I'm sorry, effective microscopy requires a nice balance between the three terms magnification resolution and contrast. And so uh if you have really great magnification, it might not matter so much if you have really, really bad resolution and really really poor contrast. And so you really need a nice balance between all three to be able to effectively use a microscope and effectively study the microbes of interest. And so this here concludes our brief introduction to these three terms magnification resolution and contrast. And moving forward, we'll be able to get some practice applying these concepts. So I'll see you all in our next video
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Problem
Problem
The resolving power of a microscope is described as the ability of the microscope to:
A
Visually separate two objects that are very close together.
B
Magnify an object.
C
Differentiate the colors of the specimen from the background.
D
See structures at various depths in a tissue.
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Problem
Problem
If you can only increase one of the following, which would you increase to observe more details of the microscopic specimen?
A
Increase the magnification.
B
Increase the resolution.
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