Laboratory Report 1 Brightfield Microscopy A. Short-Answer Questions 1. Describe
ID: 194735 • Letter: L
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Laboratory Report 1 Brightfield Microscopy A. Short-Answer Questions 1. Describe the position of your hands when carrying the microscope to and from your laboratory bench. 2. Differentiate between the limit of resolution of the typical light microscope and that of the unaided human eye (a) What two adjustments can be made to the condenser? (b) What effect do these adjustments have on the image? 3. 4. Why are condenser adjustments generally preferred over the use of the light intensity control? 5. When using the oil immersion lens, what four procedures can be implemented to achieve the maximum resolution? 6. Why is it advisable to start first with the low-power lens when viewing a slide 7. Why is it necessary to use oil in conjunction with the oil immersion lens and nos with the other objectives? 8. What is the relationship between the working distance of an objective lens and its magnification power?Explanation / Answer
1. One hand should be under the base of the microscope to support its weight, and one hand should be on the arm for balance
2. The limit of resolution of the unaided human eye is 0.2 mm. For the typical light microscope, the limit is 0.2 µm
3. a. The condenser height and diaphragm can be adjusted.
b. Illumination of the specimen is increased when the condenser is raised and the diaphragm is opened.
4. Unlike the voltage control, condenser adjustments will increase illumination without affecting the bulb life.
5. The maximum resolution with the oil immersion lens is achieved by using a layer of oil, using a blue filter over the light source, raising the condenser to its highest point, and opening the condenser diaphragm
6. The oil immersion lens has the smallest working distance and one runs the risk of striking the slide with the lens when trying to achieve focus. Starting with the low power lens, which has a larger working distance, and progressing up to the oil immersion lens is advised.
7. Oil is used with the oil immersion lens because the small working distance does not allow enough light to enter the lens. The oil, which has the same refractive index as glass, directs more light into the lens (limits the loss of light due to refraction).
8. As the power of the objective lens increases, the working distance decreases.
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