Using microscopes
What do you need to know?
What do you need to know?
The microscopes required practical is the most commonly under-revised topic as it seems easy. It is also a common area of lost marks!
Make sure you revise the names of the key parts:
- Eye piece lens (at top) - this usually magnifies the image by x10 or x5.
- Objective lens (small ones in the middle). There are usually 3-4 of these and they are different powers, ranging from x4, x10, x40 (and sometimes x100).
- Multiply the power of both lenses to get the total magnification, e.g. 4 x 5 = x20
- Coarse focus - the dial at the side is twisted to focus the image
- Do not use the phrase "zoom in" but state the image is magnified.
- The magnification be calculated using the phrase I AM - or Image = Actual size x magnification
Rearrange the equation I = AM to calculate the magnification
Rearrange the equation I = AM to calculate the magnification
Magnification = Image / Actual size
Try using the formula triangle (see below)
What is the difference between resolution and magnification?
What is the difference between resolution and magnification?
Magnification is the number of times bigger an image is compared to the actual size
Resolution is the ability to distinguish between two different points.
Light microscopes are limited by their resolution rather than magnification
What is the type of microscope called that can produce 3D images of very small objects?
What is the type of microscope called that can produce 3D images of very small objects?
Scanning electron microscope
The alternative is called the transmission electron microscope and this produces images showing sections through very small objects, e.g it can see ribosomes.
