1.32 How to Use a Microscope

This lesson looks at how to effectively use a microscope. We’ll look at the parts of a microscope and find out how, based on the lenses, we can figure out how much an object is being magnified by.

1. A Window to Another World

When you look outside, you can see many living things, like trees, people, dogs and even some bugs, with your own eyes. But what about all the living things that are too small to see? The microscopic world is a vibrant, unseen realm that can be seen using a microscope. This lesson will explore how to use a microscope so you can see these tiny things.

Examples of living things found using a microscope

1. Main points:

The text highlights the contrast between the visible world and the microscopic world, emphasizing the role of a microscope in exploring tiny, unseen living things.

2. Questions:

• Content Analysis: What kinds of living things can you see with your own eyes, and what requires a microscope?
• Contextual Analysis: Why is it important to explore the microscopic world?
• Semiotic Analysis: What does the term "microscopic world" signify in this text?

3. Further Discussion:

• If you could use a microscope right now, what tiny thing would you be most excited to see up close?

4. Answers:

• Content Analysis: "When you look outside, you can see many living things, like trees, people, dogs and even some bugs, with your own eyes."
• Contextual Analysis: The microscopic world is described as "a vibrant, unseen realm that can be seen using a microscope."
• Semiotic Analysis: "The microscopic world is a vibrant, unseen realm…" suggests that the term refers to a hidden universe of tiny living things, invisible to the naked eye but accessible through technology.

2. How to Use a Microscope

Set your microscope down on a flat surface, and grab a sample that you’d like to look at. Put your sample on a microscope slide, which is a glass rectangle that holds your sample. The slide fits on the stage of the microscope and is held down by clips. A light will shine up through the image. When you look through the top of the microscope, you can see a magnified image of your sample. This lesson focuses on compound light microscopes, which pass light through different lenses.

The part of the microscope you look through is called the ocular lens. Inside this lens is a high-powered magnifying glass. The image you see looking though the ocular lens is magnified 10 times its normal size. You’ll find other lenses on your microscope called objective lenses. By using the nosepiece, you can switch between these lenses.

Your microscope could have anywhere from one to five of these lenses. A microscope is called a compound microscope if it has many objective lenses. The objective lenses magnify your sample even more. Your sample will be less magnified by a shorter objective lens. The longer the objective lens, the more you magnify your sample.

Parts of a microscope

1. Main points:

The text provides a detailed guide on setting up and using a compound microscope, emphasizing the roles of the slide, ocular lens, and objective lenses in magnification.

2. Questions:

• Content Analysis: What steps are involved in preparing a sample for observation under a microscope?
• Thematic Analysis: What is the significance of the different lenses in a microscope?
• Socio-cultural Analysis: How might the use of a compound microscope impact our understanding of the natural world?

3. Further Discussion:

• Imagine you could look at anything under a microscope. What would you choose and why do you think it would look interesting?

4. Answers:

• Content Analysis: "Set your microscope down on a flat surface, and grab a sample that you’d like to look at. Put your sample on a microscope slide…"
• Thematic Analysis: "The part of the microscope you look through is called the ocular lens… The longer the objective lens, the more you magnify your sample."
• Socio-cultural Analysis: The text doesn’t directly address this, so we can’t provide an answer from it. However, we can infer that understanding the microscopic world expands our knowledge and appreciation of nature.

Magnification Means Multiplication

To find out how much you’re magnifying your object, you would multiply the magnification of the objective lens by the magnification of the ocular lens. So, if the objective lens is 10 times magnification and your ocular lens is 10 times magnification, you’re looking at your object 100 times larger than it is normally.

Shorter objective lenses are usually five times magnification, and larger objective lenses could be up to 100 times magnification. Multiply those by the ocular lens, and you would have one view at 50 times magnification and the other view at 1,000 times magnification. To put that in perspective, 50 times magnification would show the hairs on a spider’s legs, while 1,000 times magnification would show the details within the cells of that spider’s legs.

The size of an object if looking with a 5x objective lens

When switching to different objective lenses, you might find the stage is too high, and you can’t rotate to the longer objective lens. You can lower and raise your stage using the coarse adjustment knob. This also focuses the object in your sample. You might have to move your slide around until the object you want to see is directly in view.

Once you have your image in rough focus, you can use the fine adjustment knob to get a clearer image. Using a microscope takes practice and patience. But once you’re familiar with it, you might become addicted to finding more hidden life in the microscopic world.

1. Main points:

The text explains how to calculate the magnification level of a microscope and provides practical tips on adjusting the microscope for clearer viewing.

2. Questions:

• Content Analysis: How do you calculate the magnification level of a microscope?
• Ideological Analysis: What might be the reason for encouraging patience and practice in using a microscope?
• Thematic Analysis: What is the significance of being able to see objects at different magnification levels, like 50 times and 1,000 times?

3. Further Discussion:

• If you could magnify something 1,000 times, what would you choose to look at, and why do you think it would be interesting?

4. Answers:

• Content Analysis: "To find out how much you’re magnifying your object, you would multiply the magnification of the objective lens by the magnification of the ocular lens."
• Ideological Analysis: "Using a microscope takes practice and patience. But once you’re familiar with it, you might become addicted to finding more hidden life in the microscopic world."
• Thematic Analysis: "50 times magnification would show the hairs on a spider’s legs, while 1,000 times magnification would show the details within the cells of that spider’s legs." This shows the significant difference in detail and understanding one can gain at different magnification levels.

Lesson Summary

In this lesson, we looked at how to use a compound microscope to see the hidden microscopic world. To magnify an object, you must first place a sample on a slide and place that slide on the stage of a microscope. To determine how much an object is being magnified, you can multiply the strength of the ocular lens and the strength of the objective lens.