1. The Microscope
Images of Leeuwenhoek, electron microscope image of a fly foot
When something is hard to see with our eyes we can use a handlens or a microscope to magnify it.
Cells are extremely small 1um= m, cells are about 10 – 150ums
Uses of a microscope
Without glass, Robert Hooke, Anton van Leeuwenhoek, Robert Koch and Louis Pasteur could not have seen microorganisms under the microscope, leading to the germ theory of disease, which revolutionized medicine.
Different types of microscopes have been used to look at human cells, identify minerals, solve crimes, see how freezing affects food, study metals, and find the causes of crop diseases. Microscopes are an essential tool in medicine too. They have been used to identify the causes of many deadly diseases like malaria and tuberculosis. Microscopes can also help to find out why a person or animal died.
     Scientists can even use a microscope to figure out where illegal drugs come from. For example, looking at opium crystals through a microscope reveals different shapes depending on where the poppies they came from were grown. This information can help pinpoint the source of illegal drugs.
     You can do all kinds of amazing things at home with a microscope. Try looking at plants, paper, cloth, sugar, pond water, even the odd flea. Lots of aquarium supply stores sell tiny shrimp, called brine shrimp, which are really interesting to look at through a microscope. The possibilities for what you can find out with a microscope are endless. And who knows you might identify something new and it may even get named after you!

2. Today’s objectives To get familiar with the microscope
To learn the difference between a light microscope and an electron microscope

3. Homework
Write up today’s experiment in your labbook– title, materials, procedure, Results, conclusions

4. The light microscope Eyepiece Rough Focus Wheel Fine Focus Wheel
Nosepiece
Objective lens
Clip
Stage
Diaphragm
Mirror / Source of light
Fine Focus Wheel
Rough Focus Wheel
Eyepiece
Light microscope is also known as the compound microscope.

5. The light microscope
Light rays pass through the sample, through the lens and then into your eyes!
Best light microscope will magnify x 1000 times!
Up to x 1000 times magnification!
total magnification =
magnification of eyepiece lens x magnification of objective lens

6. The light microscope- images
Red blood cells
An egg cell

7. Transmission Electron Microscope
A beam of electrons is passed though the sample, and focussed using magnets onto the specimen.
The image can be viewed on a TV screen.
Vacuum inside the microscope as electrons woulf eb deflected by air molecules.
Electrons are invinisble to our eyes.
Up to x 500,000 times magnification!

8. Electron microscope images
A human hair
Salmonella bacterium
A scanning electron microscope picture of a nerve ending. It has been broken open to reveal vesicles (orange and blue) containing chemicals used to pass messages in the nervous system.
Pollen
A nerve ending