Microscope Basics T. Trimpe 2005 http://sciencespot.net/

Onion cells

Ocular lens (Eyepiece) Objectives Stage Stage clips Coarse Adjustment Diaphragm Fine Adjustment Light source Always carry a microscope with one hand holding the arm and one hand under the base. Base

What’s my power? To calculate the power of magnification, multiply the power of the Eye piece /ocular lens by the power of the objective. What are the powers of magnification for each of the objectives we have on our microscopes?

Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification?

Elodea
is a genus of aquatic plants often called the waterweeds described as a genus in 1803. Elodea is native to North and South America and is also widely used as aquarium vegetation. It lives in freshwater. Wikipedia

Elodea 40x

Elodea 100x

Elodea 400x

40 x 100x 400x

Discuss rules: Hold microscope with two hands Never place in direct sunlight Place sample on slide then on stage - adjust with clips Start with lowest power (shortest/ red) magnification Wind lens down a far as possible To focus slowly wind up (no fine adjustment with junior scopes) Don't look down and wind down at the same time - why ? Then increase lens power slowly - ensure lens does not touch slide

Microscope warm up Draw a small letter with a ball point pen ie 'e' Move letter left & right, up & down - record observation What is the effect called ? Increase lens power and record observation - less image seen

Aim: Review Y9 Microscope skills Try and successfully prepare an animal cell (Sheep liver cell) and a plant cell (onion cell) Task: Look at with a wet slide and draw a ‘Biological diagram’ and label all key features! onion cells (stain slide with a small drop of iodine) liver cells Extra for experts red rhubard stalk cells

Onion cells

Nature has no straight lines or 90o angles! NO Shading, no sharp curves Include: label key features with a line a heading magnification if microscope used

How to make a wet-mount slide … 1 – Get a clean slide and coverslip from your teacher. 2 – Place ONE small drop of water in the middle of the slide. Don’t use too much or the water will run off the edge and make a mess! – use a dropper… 3 – Place the edge of the cover slip on one side of the water drop. 4 - Slowly lower the cover slip on top of the drop. Cover Slip Lower slowly 5 – Place the slide on the stage and view it first with the smallest- red objective. Once you see the image, you can rotate the nosepiece to view the slide with the different objectives.