What is the Difference Between Simple and Compound Microscope

Both simple and compound microscopes are tools that help to magnify objects for closer examination. They help us see objects invisible to the naked eye by magnifying them. However, there is a difference between simple and compound microscope in terms of their lenses, magnification range, samples, etc.

What is the difference between simple and compound microscope? Simple microscope uses a single convex lens to magnify objects, whereas compound microscope uses a series of lenses (objective lens and eyepiece lens) to magnify objects.

Key Areas Covered

1. What is a Simple Microscope  
      – Definition, Features
2. What is a Compound Microscope
      – Definition, Features
3. Similarities Between Simple and Compound Microscope
      – Outline of Common Features
4. Difference Between Simple and Compound Microscope
      – Comparison of Key Differences
5. FAQ: Simple and Compound Microscope
      – Answers to Frequently Asked Questions

Key Terms

Simple Microscope, Compound Microscope

What is a Simple Microscope

A simple microscope is a basic but effective instrument that magnifies the view of objects invisible to the naked eye. It uses a single, convex lens with a short focal length. This lens is often found in magnifying glasses or reading glasses. It acts like a magnifying dome, bending light rays as they pass through. When you strategically place the object within the focal point of the lens, you can see an enlarged, virtual image. This image is erect, meaning it appears right-side up, but unlike a photograph, it cannot be projected onto a screen.

The magnification capacity is determined by the focal length of the lens and the user’s least distance of distinct vision (the closest one can comfortably focus on an object). This indicates a typical magnification range of 10x to 30x, which allows us to observe details of small objects. Although the magnifying power of a simple microscope is limited compared to a compound microscope, it is sufficient for various applications. For example, you can use it to closely examine small objects like insects, plants, and minerals.

What is a Compound Microscope

A compound microscope is a scientific instrument that helps to view magnified images of tiny objects, typically in the range of 40 to 1000 times larger than their actual size. Unlike a simple magnifying glass, which uses a single lens, a compound microscope uses a combination of lenses; hence, the name compound is given. This multi-lens system allows for much greater magnification and image detail.

A compound microscope has two lenses: the objective lens and the eyepiece lens. The objective lens is positioned closer to the specimen, while the eyepiece lens is positioned closer to the eye.

A wider magnification can be obtained by combining the magnification powers of the objective lens and the eyepiece lens. Typical objective lenses come in magnifications like 4x, 10x, 40x, or 100x, while eyepieces are often 10x. This gives total magnifications ranging from 40x to 1000x. A compound microscope generates two-dimensional images. This is because the object being observed is usually very thin and placed on a flat glass slide.

Compound microscopes are used in various fields to see the specimens, such as in biology, medicine, material science and environmental science.

Similarities Between Simple and Compound Microscope

1. Both types of microscopes are designed to magnify objects that are too small to be seen with the naked eye.
2. Both simple and compound microscopes rely on lenses to focus light and create an enlarged image of the specimen.

Difference Between Simple and Compound Microscope

Definition

• A simple microscope is a microscope with a single lens that magnifies objects for a closer view, while a compound microscope is a microscope that uses multiple lenses to provide a higher level of magnification and clarity for observing small details.

Use of Lens

• A simple microscope uses a single convex lens, similar to a magnifying glass, while a compound microscope uses a multi-lens system with two sets: objective lens (closest to the specimen) and eyepiece lens (viewed by the user).

Magnification

• A simple microscope offers a low to moderate magnification, typically limited to 300x or less, whereas a compound microscope offers a much higher magnification range, often from 40x to 1000x, due to the combined effect of objective and eyepiece lenses.

Resolution

• Simple microscopes offer a lower resolution, while compound microscopes offer a higher resolution.

Light

• A simple microscope often relies on natural light or a simple mirror to illuminate the specimen. Meanwhile, a compound microscope has an internal light source or illuminator for controlled lighting.

Condenser

• Simple microscopes do not use condenser lenses, but compound microscopes use a condenser lens to focus the light beam onto the specimen.

Position

• In a simple microscope, the object being observed is placed within the focus length of the convex lens, but in a compound microscope, the object is placed outside of the objective lens’s focus length.

Sample Thickness

• While a simple microscope is suitable for observing thin samples, a compound microscope is suitable for observing thick samples.

Portability

• A simple microscope is lighter and more portable, whereas a compound microscope is bulky and less portable.

Cost

• Compound microscopes are more expensive than simple microscopes.

Conclusion

Both simple and compound microscopes are tools that help to magnify objects for closer examination. The main difference between simple and compound microscope is the type of lenses they use.  While simple microscopes use a single convex lens for modest magnification, compound microscopes use a series of lenses, offering significantly higher magnification and image detail.

FAQ: Simple and Compound Microscope

1. Why is a compound microscope preferred over a simple microscope?

There are many advantages of compound microscopes over simple microscopes. One main advantage is that a compound microscope has high magnification and better resolution than a simple microscope, which gives a more detailed examination of small objects.

2. What are the disadvantages of a compound microscope?

Compound microscopes have some limitations when it comes to resolving fine details, especially at higher magnifications. Operating the microscope can be more complex, requiring careful alignment and adjustment for best results. In addition, the depth of field is narrow, so only a thin layer of the specimen is in focus at one time.

3. What is the use of a compound microscope?

A compound microscope is used to observe small objects and fine details that are not visible to the naked eye. It is commonly used in scientific research, education, and medical laboratories for examining cells, tissues, bacteria, and other tiny organisms.

4. What is the best microscope to see bacteria?

The best way to observe bacteria is by using a compound light microscope. This microscope has the required magnification and resolution to view bacteria.

5. Which lens is used in a compound microscope?

Two convex lenses are used in compound microscopes, one being the objective and the other being the eyepiece. A convex lens is a type of lens that is thicker in the middle and tapers to thinner edges. This shape causes light rays passing through the lens to converge or come together at a focal point on the other side.

Reference:

1. “Simple Microscope.” Encyclopedia Britannica.
2. “Compound Microscope.” Encyclopedia Britannica.

Image Courtesy:

1. “Simple microscope-MHS 466-P5200234-gradient” By Rama (CC BY-SA 3.0 fr) via Commons Wikimedia
2. “Compound Microscope” By Acagastya – Own work (CC0) via Commons Wikimedia