What should be done first when aligning the light for a reading microscope?
Light alignment for a reading microscope is a critical step in microscope operation. Some students use any objective lens to align light instead of following the requirement to use a low-power objective lens. When rotating the revolving nosepiece, they often press the reflector down.
Therefore, instructors must emphasize the correct light alignment method during guidance. Use a small aperture and plane mirror in bright light conditions, and switch to a large aperture and concave mirror in dim light. Rotate the reflector with both hands until a uniformly bright circular field of view is obtained. Do not arbitrarily move the microscope after light alignment, otherwise the light may fail to pass through the aperture accurately.
The diaphragm has round holes of varying sizes, known as apertures. Adjusting different apertures to align with the light passage hole can regulate light intensity. Specimens are generally placed at the center of the light passage hole for convenient observation.
Total magnification refers to the product of the eyepiece magnification and objective lens magnification. The closer your eye is to the eyepiece, the better. The lengths of eyepieces and objective lenses relate to magnification. The distance between the objective lens and the slide has no correlation with magnification. A higher magnification results in larger cells but fewer cells visible in the field of view. Magnification has no effect on the brightness of the field of view, which is controlled by the reflector and diaphragm.
Move the eyepiece: if dirt moves, the dirt is on the eyepiece.Move the objective lens: if dirt moves, the dirt is on the objective lens.Move the slide: if dirt moves, the dirt is on the slide.Keep other components stationary and move only one part at a time to locate contamination.
Switch from low-power lens to high-power lens.
Similarities: All cells possess cell membranes, cytoplasm, ribosomes and nucleic acids. All cellular organisms contain DNA and RNA, and DNA serves as their genetic material.
Differences: The essential difference is that prokaryotes do not have a membrane-bound, well-defined nucleus.
