Question

1. Now, focus on your specimen using each of the other objective lenses (i.e. 10x, 40x, and 100x). Then, answer these questions:

1. After you have your specimen focused and centered on the 4x objective lens, do you need to move the stage down before you switch to the 10x objective lens? Type your answer below.

2. As you progress from the smallest objective lens (i.e. 4x) to the largest objective lens (i.e. 100x), describe what occurs to the brightness of the specimen. Type your answer below.

3. To address the issue you described in the previous question, which part of the microscope would you have to adjust? Type your answer below.

4. What happens when you use the course adjustment knob while either the 40x objective lens or 100x objective lens is set in place? Type your answer below.

5. Once you have your specimen in focus and centered using the 100x objective lens, take a screen shot of what you see. Then, paste that screen shot in the space below:

Answer 1

a) Yes, the stage needs to be moved down before switching up to the 10x objective lens. This is because of the fact that the length of 10x lens setup (its tube) is longer than the length of 4x lens setup (its tube). So due to longer length, the lens might collide with the stage or specimen, hence scratching or damaging the setup.

b) As we move from the smallest objective lens (i.e. 4x) to the largest objective lens (i.e. 100x), the overall brightness of the specimen will decrease. This is because magnification and brightness follow an inverse relation, with brightness changing as inverse square of magnification. Brightness decreases due to reduction in working distance between specimen and lens, hence permitting less light to enter inside.

c) To address the above issue, we need to increase the brightness as we keep increasing the magnification. It can be done by either increasing the illumination of the lamp, or adjusting the iris diaphragm a bit wider than previous level.

d) When we use coarse adjustment knob at higher magnifications (say 40x or 100x), then there is a high risk of crashing or colliding the specimen with the lens. Coarse Adjustment knob moves the specimen slide by large distance at rapid rate. The distance between slide and lens is very low at 40x and 100x. So by using coarse adjustment knob instead of fine adjustment knob, the specimen will get smashed to the lens and damaging the microscope.

e) To be done by student itself

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