Microscopy

To define magnification and resolution.
To compare and contrast light microscopes and electron microscopes in terms of their principles, magnification, and resolution.
To apply the magnification formula and understand the use of standard form in representing the size of microscopic objects.

In biology, we often study extremely small structures like cells that cannot be seen with the naked eye.
Microscopes are essential tools for this, and their quality depends on two main features:
- Magnification: The ability to make objects appear larger.
- Resolution: The ability to distinguish between two close points, creating a sharper image.

Comparing magnification and resolution

Light Microscopes:
- First developed in the late 16th century, these microscopes use light and glass lenses to magnify images.
- Although they have relatively low magnification and resolution, they allow us to observe basic cell structures like the nucleus, vacuoles, and chloroplasts.
Electron Microscopes:
- Invented in the early 20th century, electron microscopes use electrons instead of light and electromagnets instead of lenses.
- They offer much higher magnification and resolving power than light microscopes, allowing scientists to study cells in much finer detail.
- This advanced resolution has enabled biologists to see and understand sub-cellular structures such as mitochondria, ribosomes, and even viruses.

A light microscope

magnification = size of image / size of real object

In this formula:
- Size of image is how large the object appears under the microscope.
- Size of real object is the actual size of the object being viewed.
When biologists observe and draw what they see under a microscope, the drawing represents the image, and the real object is the actual cell or structure.
The magnification shows how much the object has been enlarged in the drawing.

To work with very large or very small numbers in a manageable way, scientists use standard form.
This notation expresses numbers with a single digit before the decimal, followed by "x10" raised to an exponent, which represents the number of places the decimal has moved.
Examples:
- 0.001 can be written as 1 x10-3
- 170,000 can be written as 1.7 x105
- 0.0000823 can be written as 8.23 x10-5
Using standard form helps simplify calculations and comparisons, particularly when dealing with extremely small or large measurements in microscopy.

Microscope: An instrument used to magnify objects too small to be seen with the naked eye.
Magnification: The process of making an object appear larger than its actual size.
Resolution: The ability of a microscope to distinguish between two separate points, resulting in a clear image.
Light microscope: A microscope that uses visible light and lenses to produce a magnified image.
Electron microscope: A microscope that uses a beam of electrons and electromagnets to produce a highly magnified and resolved image.
Standard form: A way of writing very large or very small numbers using powers of 10 (e.g., 1×10−3).
Size of image: The apparent size of an object as seen through a microscope or in a drawing.
Size of real object: The actual, true size of the object being viewed.

Microscope History Timeline: Research the history of microscopy, creating a timeline highlighting key inventors, developments (like the first light microscope or electron microscope), and the impact of these inventions on biological discovery.
Calculating Magnification Practice: Find microscope images online or in textbooks with a scale bar. Use the magnification formula to calculate the actual size of different cells or organelles shown in the images.