Microscope Basics

Parts of the Microscope

1 . Eyepiece : the part that you look through (closest to the eye) usually 10x2. 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 MagnificationIf 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?• 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)

Under microscope

FActual Image

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 MicroscopesElectron 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: 1.5mmConvert to micrometers1 mm = 1000 micrometersSo 1.5 mm = 1,500 micrometers(Move decimal over 3 to right)

Finding Field of View (F.O.V)• Under Medium or High

PowerNeed to set up a proportion

Remember!! • As magnification

increases FOV decreases

Low power Magnification = High power FOVHigh power Magnification Low power FOV

Ex: 100x = HP FOV500x 1500 micrometers

500x = 150000HP 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 power2) 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 10x2. _____________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 MagnificationIf 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?• 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)

Under microscopeActual Image

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 MicroscopesElectron 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: 1.5mmConvert to micrometers1 mm = _______________________So 1.5 mm = 1,500 micrometers(Move decimal over _______________)

Finding Field of View (F.O.V)• Under Medium or High

PowerNeed to set up a proportion

Remember!! • As magnification

increases FOV decreases

Low power Magnification = High power FOVHigh power Magnification Low power FOV

Ex: 100x = HP FOV500x 1500 micrometers

500x = 150000HP 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 power2) _____________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?