Overview
This lecture introduces the key components and concepts of light microscopy, focusing on how microscopes work and defining important terms like object, image, magnification, and resolution.
Parts of a Light Microscope
- The base supports the entire microscope.
- The arm connects the base to the top section.
- The light source (lamp or mirror) provides illumination.
- The stage holds the microscope slide with the sample.
- Objective lenses offer different magnifications (e.g., 10x, 20x, 50x).
- The eyepiece lens at the top has a fixed magnification.
- The body tube connects the lenses.
- Coarse and fine focusing knobs adjust the focus.
Key Terms in Microscopy
- The object is the actual sample (e.g., onion cells) on the slide.
- The image is what you see when looking through the microscope.
- Do not confuse object (physical specimen) with image (visual output).
How Light Microscopes Work
- Light is reflected by a mirror (or emitted by a lamp) through the object on the stage.
- Light passes through the objective lens, then the eyepiece, and enters the eye.
- Lenses spread out light rays to make the image appear larger than the object.
Magnification
- Magnification is how many times larger the image is compared to the object.
- Magnification formula: Magnification = Image size ÷ Object size.
- Example: If image is 1000x larger than the object, magnification is 1000x.
Resolution
- Resolution is the shortest distance between two points that can still be distinguished.
- Higher resolution means more detail and less blurriness.
- Two images with the same magnification can have different resolutions; higher resolution is clearer.
Key Terms & Definitions
- Object — the actual specimen being observed on the microscope slide.
- Image — the enlarged visual representation seen through the microscope.
- Magnification — the ratio of image size to object size.
- Resolution — the smallest separation between two points that can be distinguished as separate.
Action Items / Next Steps
- Practice microscope questions using the provided link or pinned comment.