Parts & Processes of a Microscope Structures of a Microscope Functions of a Microscope How Microscopes Work

The Big Idea? What are the parts of a “Compound Microscope” & How do “Compound Microscopes” uses lenses to magnify objects

Student Handout Follow along with your handout and fill in the questions as we work through the material Green check marks will clue you into when you should be getting that info down on your handout

History of the Microscope A man named Leeuwenhoek was the first to experiment with his own microscope in the 1600’s He looked at pond water, blood, and plaque from his teeth His discoveries shocked the scientific world and people were opened up to a whole new world… microbiology

What Does It Do? The microscope is designed to collect and gather light from small objects and enhance the image for us to see There is a limitation to the microscopes capability, what is that limitation?

What’s the Limitation Some objects are just too small to reflect enough light for the microscope to catch and create an image out of… they don’t have the relevant surface area like larger objects to reflect enough light for our eyes to detect This is why we can’t see many small micro organisms with conventional light microscopes… there just isn’t enough light So what can we do if we want to see extremely small items?

Electron Microscopes We can use electron microscopes to magnify up to x as compared to a conventional microscope that might magnify up to 500 x or 800 x Unfortunately what ever we are looking at has to be dead! How do they work?

Today’s Microscopes Most of today’s microscopes, including the microscopes in this room, have a light underneath that is designed to shine more light on to smaller objects in attempts to allow us to see the image

In Your textbooks! Open to page 103 – 107 in the “Science Focus” textbook and follow along as we go through some of the material on magnification Once we have read over the information, you are responsible for filling out the back side of your handout Pages 98 – 101 in the “Science in Action 8” Textbook could also be helpful

The Flip Side Take sometime to fill out the flip side of that sheet and then double check your answers with a neighbor… will be reviewing it in about 5 minutes Note that in your text book they call part 1 the eye piece… this is incorrect for our purposes Call that piece the Ocular Lens Also, the bottom is called the Base

Nose Piece Stage Clips Objective Lens Diaphragm Lamp Ocular Lens Base Fine Adjust Coarse Adjust Stage Arm Eye Tube

Compound Microscopes Compound microscopes use two lenses in series to magnify an image… they compound one and other, hence the term “compound microscope” The two lenses are the OBJECTIVE LENS and the OCULAR LENS In order to calculate the total magnification taking place on the image… simply multiply the magnification power of both lenses together OCULAR POWER x OBJECTIVE POWER = TOTAL MAGNIFICATION

Calculated Magnification You now have a number (product) from the two lenses That number represents how many times larger the image you see in the microscope is than if you where to look at the object with your naked eye i.e. ocular lens is 5 x and the objective lens is 30 x 5 x 30 = 150 total magnification no magnification 150 magnification

Practice Makes Perfect Question 5 Ocular lens is 5 x and the Objective lens is 10 x What is the total magnification of the image? 5 x 10 = 50 therefore the total magnification is 50 and object appears to be 50 times larger than when seen with the naked eye Who will do it on the board??

Practice Makes Perfect Question 5 Ocular lens is 5 x and the objective lens is 10 x What is the total magnification of the image? 5 x 10 = 50 Therefore the total magnification is 50 and object appears to be 50 times larger than when seen with the naked eye

Practice Makes Perfect Individually, try the next three examples on your handout We will go over them shortly but you should be able to have this simple calculation down by the end of this class Volunteers will be needed to show us how you figured out the magnification level on the BOARD!!!

Practice Makes Perfect a) High level objective lens Ocular lens = x 45 = 450 magnification Objective lens = 45 b) Low level objective lens Ocular lens = x 5 = 50 magnification Objective lens = 5 c) Medium level objective lens Ocular lens = x 12 = 120 magnification Objective lens = 12

Study Up Hang onto these sheets and file them into your note book in the proper order for this unit Save the sheets for study purposes There will be a QUIZ on what we covered today as well as the material we will cover in the next couple classes so STUDY UP