Alizée Razavi SNC2D October 22, 2019 Lesson 2 Assignment: Using a Compound Microscope Microscopes have been the ever evolving invention to cause numerous transformative breakthroughs in biology such...

Alizée Razavi SNC2D October 22, 2019 Lesson 2 Assignment: Using a Compound Microscope Microscopes have been the ever evolving invention to cause numerous transformative breakthroughs in biology such as: the establishment of microbiology, the study of microorganisms or the unrecognized discovery and naming of cells. The compound light microscope is most commonly used because it is both affordable and readily available. This microscope uses light for illumination and allows the observer to view thin layers of a specimen at relatively low magnification. The image below shows the 12 main parts of the microscope followed by a list of their functions: 1. The body tube connects the ocular lens to the objective lenses. 2. The revolving nosepiece holds the objective lenses whilst also rotating when needed to change magnification. 3. There are 3 powers of objective lenses: the low power objective has the lowest power in comparison to the other objective lenses (generally having a magnification of 10x). The high power objective has the highest magnification (generally having a magnification of 100x). The medium power objective has a power that ranges in between the low and high objective lenses (generally having a magnification of 40x). 4. The slide containing your specimen is held in place by the stage clips. 5. The diaphragm regulates the amount of light that passes through the slide. 6. The lightsource is the microscopes source of light. 7. To view the slide you must look through the ocular lens (eyepiece) (generally has a magnification of 10x). 8. The arm provides support and connection of the base and body tube. 9. The stage is where the slide in placed. 10. The coarse adjustment knob is used to focus the image of the slide by a large amount. 11. The fine adjustment knob is used to focus the image of the slide by a small amount. 12. The base is the bottom of the microscope that holds all the parts. To properly and safely set up a compound light microscope you must first find your microscope and carry it with two hands (as a safety precaution to avoid damaging the microscope and injuring yourself); one hand under the base and one holding the arm. Be mindful of your surroundings as you slowly walk to a flat and steady surface to gently put down your microscope. Now press the on button to turn on the microscope (plug in if needed). Carefully pick up your slide and place it on the stage so that the stage clips can hold it in place. It is important to start with the lower objectives first; focus it and then move on to a higher power objective because the low power objective lens has a larger field of view making it easier to locate the specimen. The steps are the same for switching to any power objective lense first turn the coarse adjustment knob to move the stage to its max height to ensure the slide dosen’t move or break. Then to switch between different object lenses turn the revolving nosepiece to the desired objective lense so that it is perpendicular to the stage and clicks in place. Look through the eyepiece (the image will appear upside down and backwards because of the two mirrors that are within the microscope) if the image is not in focus then to focus the slide by a large amount slowly turn the coarse adjustment knob however do not use this knob with the high power objective lense because the specimen will move in and out of focus to fast making it difficult to accurately focus the image; there is also the risk that the coarse adjustment knob will move the stage to quickly leading it to crash into the lense. To focus the slide by a small amount turn the fine adjustment knob. Continue to look through the eyepiece and turn the coarse and fine adjustment knob until the specimen is in focus. For example to switch from the medium power objective lense to the high power objective lense you would do the following: 1. Bring the stage to its maximum height using the coarse adjustment knob. 2. Rotate the revolving nosepeice so that the high power objective lense clicks in place of the medium power objective lense. 3. Look through the eyepiece whilst turning the fine adjustment knob to focus the image.