Learning Objectives:

To be able to:- Label and give the function of each part of the

microscope.- Use the microscope correctly to view slides and

work out magnification.

The Microscope

What do all the organisms below have in common?

Red Blood Cells

E. Coli Bacteria

Dust Particles

Ebola Virus

Daphnia

Water Bear

The are all microscopic organisms. They cannot be seen with the naked eye, we need a microscope to

see them.

Microscopy• Microscopy is the use

of or investigation with a microscope.

• The microscope uses glass lenses to magnify objects we are not able to see clearly with the naked eye.

Since the 1st Century the Roman's, were investigating the use of glass and how to magnify objects. Nero (reigned 54–68 AD) is also said to have watched the gladiatorial games using an emerald as a corrective lens!

In the 13th Salvino D'Armate from Italy, made the first eye glass.

The earliest simple forms of magnifying glasses were used for inspecting tiny insects such as fleas, hence these early magnifiers called "flea glasses".

• In the 1590's, two Dutch spectacle makers, Zacharias Jansen and his father Hans started experimenting with these lenses. They put several lenses in a tube and made a very important discovery. The object near the end of the tube appeared to be greatly enlarged, much larger than any simple magnifying glass could achieve by itself. This was the first compound microscope.

• It was Anton van Leeuwenhoek (1632-1723), a Dutch draper and scientist, and one of the pioneers of microscopy who in the late 17th century became the first man to make and use a real microscope. He was known as the “Father of Microbiology”.

• Van Leeuwenhoek achieved greater success than his contemporaries by developing ways to make superior lenses, grinding and polishing five hundred and fifty lenses to make his new lens tube that had a magnifying power over 200 times better than any one else at the time

• Light• A

compound microscope uses more than one lenses

• Electron microscope uses

Different types of

microscopes

The Light Microscope has 1 compound lens

The Electron Microscope has 2+ compound lenses

Human hair

Light microscope

Electron microscope

Using the Microscope1. Always carry the microscope by the base

and the arm.2. Use the lowest objective power lens first.3. Angle the mirror or adjust your light to let

in plenty of light.4. Place the slide you want to look at on the

stage.5. Turn the course focusing wheel until you

can see your slide clearly.6. Then adjust your image with the fine

course focusing wheel7. You may now use the higher objective

lens, taking care to move the stage slowly so as to avoid the slide touching the lens.

The Light Microscope

The Light Microscope

Match the part with its function!Part Function

Eyepiece Lens

Controls the amount of light that goes onto the microscope slide.

Objective Lens

This is the lens closest to your eye. It usually has a magnification of x10

Stage This is used to focus the image so it is very sharp and clear.

Diaphragm This is used to focus the image so that you can see it clearly.

Light This holds the eyepiece lens above the stage.

Base There are three lenses of different strengths which can be used to magnify the image more clearly.

Arm This is the place where you put a microscope slide. Clips hold the slide in place

Fine Focus Knob

The light source projects light onto the microscope slide. It can be a mirror or an electric bulb.

Coarse Focus Knob

This is very heavy to keep the microscope from falling over

How to work out magnification!

Magnification = Eyepiece Lens x Objective lens

If the eye piece lens has a magnification of 10x and the objective lens has a

magnification of 40x then the image will be magnified 400x! 10x x 40x =400x

Eyepiece Magnification

Objective Magnification

Total Magnification

10x 4x 40x

10x 5x 50x

5x 40x 200x

5x 120x 600x

5x 100x 500x

10x 125x 1250x

Drawing Microscope Slides / Specimens:• Use a pencil• Draw only the lines you see. No shading or colouring• Each circular diagram (field of view) should be about

a 3rd of a page in size• If the cells you are viewing are similar/repetitive it’s

useful to draw about 4-5 only

Always record the:magnification name of specimen and the date of the

observation

1. Carefully peel back a layer of onion with the tweezers – thinner the better.

2. Place the onion on the slide as flat as possible.

3. Put two drops of iodine on top of the onion (IODINE STAINS).

4. Place the coverslip over the top without bubbles being trapped underneath.

5. Look through microscope at cells.

Preparing onion cells