Biology- Microscopes and Magnification Flashcards
What is the ‘magnification’ equation?
Magnification = ?
Magnification =
size of image / actual size of the object
(/ means divided by)
Mag = I / A
Unit conversions
1 m = ? cm = ? mm = ? micrometer
1m = 100 cm = 1000 mm = 1,000,000 micrometer
What is the symbol for micrometre?
Learn it (google it)
It is a Greek letter (like an m with a tail going down on the left hand side)
If you are doing calculations of magnification what should you do first ?
You should check that………
The units of the image size and the actual size are the same.
This is called standardising the units.
What is a microscope used for ?
To enable you to see things you can’t see with the naked eye.
Parts of a microscope (look in CGP book page 1)
Does a microscope have more than one lens?
Yes
It has an eye piece lens as well as high and low power objective lenses
Parts of a microscope (look in CGP book page 1)
Where is the sample placed
On a microscope slide which is then placed on the STAGE of the microscope
Parts of a microscope (look in CGP book page 1)
How do you see a clear image?
You look through the eyepiece while you focus the microscope.
To do this, you focus the image by turning the focussing knobs on the side.
There are two
Rough focus knob , you use this one first to get it roughly focussed
Fine focus knob. You use this one last to get a clear image.
Parts of a microscope (look in CGP book page 1)
When would you use the high powered objective lens?
To make the image bigger.
What are light microscopes good at looking at?
Cells
E.g epithelial cells
Root hair cells
Nerve cells
Palisade cells
Light microscopes can achieve up to magnification of ?
Depends on the microscope but up to about x 1000
Describe how a light microscope works , see picture in CGP book page 1
In this question , how do you prepare the sample
Objects placed on slide
Stained (with a dye to help you see it)
Place a coverslip over it
Place slide on the stage
Describe how a light microscope works , see picture in CGP book page 1
When the slide is on the stage what do you do next?
Turn on the microscope, the light shines and illuminates the sample (so you can see it )
and then focus on the sample (adjust the focussing knobs) so you can see it clearly.
Can you see the structure of organelles within a cell using a light microscope ?
No you would need to have an electron microscope which has more powerful magnification
So by using an Electron microscope you can study cells in much finer detail.
If a microscope has a higher magnification , it has greater R?
Resolution
