Microscope Basics

Parts of the Microscope 1 . Eyepiece : the part that you look through (closest to the eye) usually 10x 2. Objective Lens : the magnifying part closest to the slide (high power=usually 40x; low power=usually 10x) 3. Fine Adjustment Knob : used to focus on low & high power 4. Coarse Adjustment Knob : used to focus only on low power 5. Stage : where the slide is placed 6. Stage Clips : hold the slide in place 7. Diaphragm : controls the amount of light used

Calculating Magnification If a microscope has a 10X eyepiece, and 10X and 40X objectives. Total Magnification on low power : 10 X 10 = 100X ( it looks 100 times bigger than real life) Total magnification on high power : 10 X 40 = 400X (it looks 400 times bigger than real life)

Is what we see under a microscope EXACT? Actual Image Under microscope F When we view objects under the microscope… 1. We see a mirror image that is flipped up side down. 2. Increasing magnification reduces the field. (Larger image but you see less of it) 3. Increasing the magnification reduces the amount of light. (Field darkens)

How to make a wet mount slide: Put the cells on the center of a slide, put a drop of water with a dropper onto the cells (do not touch the cells) Lower a cover slip slowly at an angle (to reduce the number of air bubbles) Too much water? Use a paper towel to absorb excess liquid.

Types of Microscopes: Light microscopes: - Around 1600 The ones that WE use! Lenses made of glass or plastic Maximum = 2000x larger

Types of Microscopes Electron Microscopes: -1930 -View molecules and atoms, smaller images than a light microscope -1st type= Transmission Electron Microscope (TEM) - beams of electrons - resolution = 1000x better than light microscope

SEM Scanning Electron Microscope 1935 Better depth of view, higher resolution, more detailed surface picture resolution: A measure of the clarity of an image; the minimum distance that two points can be separated by and still be distinguished as two separate points.

Important Units for Microscopes Micrometers (microns) = µm 1/1000th of a millimeter 1000 micrometers = 1 mm How big is a micron? 

Finding Field of View (F.O.V) Under Low Power: Use millimeter ruler Ex: 1.5mm Convert to micrometers 1 mm = 1000 micrometers So 1.5 mm = 1,500 micrometers (Move decimal over 3 to right)

Finding Field of View (F.O.V) Under Medium or High Power Need to set up a proportion Remember!! As magnification increases FOV decreases Low power Magnification = High power FOV High power Magnification Low power FOV Ex: 100x = HP FOV 500x 1500 micrometers 500x = 150000 HP FOV = 300 micrometers

Practice: A student determines that the field of view with a 10 X ocular and a 4 X objective is 2.1 mm in diameter. What is the diameter of the field of view with the same ocular and a 40 X objective?

Determining the Size of an Object Under a Microscope 1) View and draw object on low power 2) Estimate how many objects would fit across diameter of field of view Divide the diameter of FOV by the number of objects that can fit across it. Ex: Three letter “e”s fit across FOV of 1800 micrometers Each letter is about 600 micrometers 1800 micrometers = 600 µm 3 letter “e”

Practice:

1. What is the primary difference between a low - power objective and a high - power objective? 2. What is the total magnification of a microscope with a 15 X ocular and a 40 X objective?

STUDENT NOTES

Microscope Basics

Parts of the Microscope 1 . ____________: the part that you look through (closest to the eye) usually 10x 2. _____________Lens : the magnifying part closest to the slide (high power=usually 40x; low power=usually 10x) 3. __________________Knob : used to focus on low & high power 4. _____________Adjustment Knob : used to focus only on low power 5. ____________: where the slide is placed 6. ________________: hold the slide in place 7. __________________: controls the amount of light used

Calculating Magnification If a microscope has a 10X eyepiece, and 10X and 40X objectives. Total Magnification on low power : ( it looks __________times bigger than real life) Total magnification on high power : (it looks 400 times bigger than real life)

Is what we see under a microscope EXACT? Actual Image Under microscope When we view objects under the microscope… 1. We see a ________________that is ____________________________. 2. ______________magnification _________the field. (Larger image but you see less of it) 3. ______________the magnification _____________the amount of light. (Field darkens)

How to make a wet mount slide: Put the cells on the _______________, put a _______________ with a dropper onto the cells (do not touch the cells) Lower a cover slip ___________________________(to reduce the number of air bubbles) Too much water?

Types of Microscopes: Light microscopes: - Around 1600 The ones that WE use! Lenses made of glass or plastic Maximum = 2000x larger

Types of Microscopes Electron Microscopes: -1930 -View molecules and atoms, smaller images than a light microscope -1st type= Transmission Electron Microscope (TEM) - beams of electrons - resolution = 1000x better than light microscope

SEM Scanning Electron Microscope 1935 Better depth of view, higher resolution, more detailed surface picture resolution: A measure of the clarity of an image; the minimum distance that two points can be separated by and still be distinguished as two separate points.

Important Units for Microscopes Micrometers (microns) = µm 1/1000th of a millimeter 1000 micrometers = 1 mm How big is a micron? 

Finding Field of View (F.O.V) Under Low Power: Use millimeter ruler Ex: 1.5mm Convert to micrometers 1 mm = _______________________ So 1.5 mm = 1,500 micrometers (Move decimal over _______________)

Finding Field of View (F.O.V) Under Medium or High Power Need to set up a proportion Remember!! As magnification increases FOV decreases Low power Magnification = High power FOV High power Magnification Low power FOV Ex: 100x = HP FOV 500x 1500 micrometers 500x = 150000 HP FOV = 300 micrometers

Practice: A student determines that the field of view with a 10 X ocular and a 4 X objective is 2 .1 mm in diameter. What is the diameter of the field of view with the same ocular and a 40 X objective?

Determining the Size of an Object Under a Microscope 1) ________and ____________object on low power 2) _____________how many objects would fit across diameter of field of view Divide the diameter of FOV by the number of objects that can fit across it. Ex: Three letter “e”s fit across FOV of 1800 micrometers Each letter is about 600 micrometers

Practice:

1. What is the primary difference between a low - power objective and a high - power objective? 2. What is the total magnification of a microscope with a 15 X ocular and a 40 X objective?