Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The Microscope We use the microscope to look at objects that are too small for us to see with the unaided eye. This is a Compound Microscope (compound because it uses a series of lenses rather than only one), and to use it you must have care! When we move a microscope we always make sure the chord is wrapped around the base and we hold it by the arm, and have our second hand under the base. In addition to the terms in the diagram you should be familiar with the following: The eye piece or ocular lens is located at the top of the microscope in the tube. There are also 3 objective lenses that have different magnifications. These are located on the rotating piece above the stage. In order to determine the magnification of anything we look at, we need to multiply the magnification of the ocular lens x the magnification of the objective lens. For example: If the ocular lens has a magnification of 10x (marked on the lens) and the magnification of the objective lens is 10x (also marked on it) Total magnification = 10 x 10 = 100x (the times is added to complete the thought.) It is imperative that when you start to use the microscope, you start with the lenses as far away from the sample as possible, and that you start with the lowest magnification. Once the sample has been placed on the slide, you may use the coarse-adjustment to bring the sample into focus. To sharpen the image, use the fine-adjustment. Only after the sample has been put into focus on the lowest magnification may you rotate the ocular lenses to the next highest magnification. At this level only use the fine-adjustment knob to bring it into focus. If you do not do as directed, you will damage your sample and possibly the lens. Pay attention to all other safety rules outlined to you to make sure you have a successful experience. Preparing a Scientific Drawing Rules: Usually a maximum of two drawings per page On only one side of page Must be large enough to show small details and make sure they can be labelled Shading and stippling (small dots with a sharp pencil), may be used but only if absolutely necessary (It is better to describe extra detail in your observations) Labels should be in pencil and printed neatly with connecting lines to the feature. All labels should be on the right-hand side of the drawing and should be aligned vertically Lines to the labels cannot cross each other and cannot have arrow heads. Try to make them horizontal. The title or description should be below the drawing and the magnification should be indicated at the bottom right of the drawing. Magnification = 20x The Earthworm Find the magnification of your microscope: Fill in the table below so that you can calculate the magnification Eyepiece (ocular lens) Objective lens Using the lowest magnification: Mount a piece of newspaper and look at a letter. Draw its orientation? What does the microscope do? ___________________ _____________________________________________ _____________________________________________ Magnification Using a transparent mm ruler, determine how large your field of view is under each magnification Lowest Magnification = ________ Medium Magnification = ________ Largest Magnification = _________ Extra: Prepare a slide by dampening the surface of the slide with water using your finger tip. Now place with a few grains of salt or a piece of human hair on the slide. Using the ruler how large do you think it is? State the magnification and estimated size in mm ________________ _________________ Draw the image in the space provided Preparing your slide for the onion skin 1. Pull off one section of the onion skin. Using tweezers or your fingers pull off the inner skin. (Be very careful not to touch your face or rub your eyes after touching the onion – it is an irritant) 2. Place the skin as flat as possible on the slide (try not to allow any of it to overlap). 3. Add 1 drop of iodine to the skin. Iodine is a type of stain so make sure not to get it on your clothing or skin. The iodine will colour your skin and allow you to see more of its features. 4. Place your cover slip on your slide – your teacher will provide the best method. 5. Draw the medium and high power images on a separate sheet of white paper. Use the instructions for a scientific drawing and try to match some of its organelles with those shown by your teacher. 6. Make sure to hand in your drawing at the end of class.