Practical 2 - Calibration Of The Light Microscope At Low To High Power + Magnification Calculation O A Drawing Flashcards
Name 5 key parts of the microscope
-Focus wheels
-Objective lenses
-Slides
-Stage
-Eye piece
What’s the name of the lenses on a microscope?
Objective lenses
What do you look into on a microscope?
Eye piece
What do you use to focus on a microscope?
Focus wheels
What do we need to fit the eye piece with in this experiment?
An eye piece graticule
What do we need for this experiment?
-Microscope fitted with eye piece graticule
-Stage micrometer
-Microscope slide + cover slip
-Paper towel
What do we measure in on an eye piece graticule?
Eye piece units (epu)
How many eye piece units are on an eye piece graticule?
100
How do we calibrate a microscope?
Using a stage micrometer, you line its zero up with the eye piece graticule’s zero, ensuring they’re parallel.
Stage micrometer units divided by eye piece units = stage mm units
1 epu: answer x one stage mm unit
= answer in mm
(Can x1000 to get in micro metres)
How do we measure the length of each division on the eye piece graticule at different magnifications?
Use a stage micrometer
What are the two options of stage micrometers to use, and what is the value of 1 unit on each of these?
1mm (1 unit = 0.01mm)
10mm (1 unit = 0.1mm)
What’s the method for this experiment?
- Calibrate from low to high power
- Take 1 human hair + water + cover with slip on the slide + press with paper towel
- Measure the width of the hair in eye piece units + use calibration to calculate the actual size
- Draw section of hair and use the method to calculate its magnification
Magnification formula
i
——
a I m
(Triangle)
What’s the magnification at low power on the microscope we used?
40x
What’s the magnification at medium power on the microscope we used?
100x
What’s the magnification on high power on the microscope we used?
400x
What’s the calibration at low power (40x)?
0.025mm
What’s the calibration at medium power (x100)?
0.01mm
What’s the calibration at high power (400x)?
0.0025mm
What does the calibration actually mean?
Every one of the eye piece units is this much
How do we calculate the actual size of the hair?
Eye piece units x calibration at this size
What do the 6 differences between the light and electron microscope cover?
Beam of ________
Wavelength of beam
Images
Specimens
Resolution power
Magnification
Compare the beams between light and electron microscopes
Light - beam of light
Electron - beam of electrons
Compare the wavelength of the beams from the light and electron microscopes
Light - longer wavelength
Electron - shorter wavelength
Compare the images produced by the light and electron microscope
Light - colour
Electron - black and white only
Compare the specimens that can be observed using a light and electron microscope
Light - can see live specimens
Electron - only dead specimens
Compare the resolution powers in light and electron microscopes
Light has lower resolution than electron
Compare the magnification between the light and electron microscopes
Light has lower magnification than electron
What does the fact that the electron microscope has higher resolution and magnification mean?
We receive images that are much clearer and in greater detail
Why is staining used?
To give a contrast between cell structures
Can we use staining to observe live cells? Why?
No, as it kills them
What is one unit of the 1mm stage micrometer?
0.01mm
What is one unit of the 10mm stage micrometer?
0.1mm
Magnification
How many times bigger the image is compared to the object
How many times bigger the image is compared to the object
Magnification
Resolving power
the minimum distance by which two points must be spectated in order for them to be seen as two distinct points other than a single focused image
The minimum distance by which two points must be spectated in order for them to be seen as two distinct points other than a single focused image
Resolving power
