Magnification and calibration - 2.2 (1) Flashcards
Module 2, Chapter 2, 2.2, Page 15
What is magnification?
how many times larger the image is than the actual size of the object being viewed
What do the interchangeable objective lenses on a compound light microscope allow a user to adjust?
the magnification
What cannot be done just by simply magnifying an object?
increasing the amount of detail that can be seen
What also needs to be increased apart from magnification?
the resolution
What determines the amount of detail that can be seen?
the resolution of a microscope
The higher the resolution…
the more details are visible
What is resolution?
it its the ability to see individual objects as seperate entities
What is resolution limited by?
the diffraction of light as it passes through samples (and lenses)
What is diffraction?
it is the tendency of light waves to spread as they pass close to physical structures that are present in the specimens
How are the structures in the specimens arranged?
very close to eachother
What can happen as an outcome when the light is reflected from individual structures in the specimen?
the light can overlap due to diffraction
In optical microscopy, structures that are closer than half the wavelength of light cannot be…
seen seperately
How can resolution be increased?
by using beams of electrons which have a wavelength thousands of times shorter than light
What is still diffracted?
electron beams
What is meant by the shorter wavelength through electron beams?
individual beams can be much closer before they overlap
Objects which are much smaller and closer together…
can be seen separately without diffraction blurring the image
What is the magnification formula?
magnification = size of image / actual size of object
The size of the image refers to the…
length of the image as measured, for example with a ruler
What do you need to change to that of the actual size of the object?
the units of measurement
Can the magnification formula be rearranged to find any of the unknowns?
yes, through the three-part formula triangle
