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10 Cards in this Set
- Front
- Back
Name the contribution of Hooke, Van Leeuwenhoek, Abbe, & Köhler to microscopy.
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Hooke: described the structures seen on cork as ‘cell’
Van Leuwenhoek: “simple” microscope that could magnify much better, to about 275x with simple ground lenses Abbe: defined physical laws that determine resolving distance of an objective, used oil emersion to increase resolution Kohler: developed the “Köhler Illumination” which is improving resolution by using shorter wavelength and evenly illuminated field by using very wide cone of light |
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Define the following: a. Absorption, b. Refraction, c. Dispersion, d. Refractive index.
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Absorption: light passes through an object the intensity is reduced depending on the colour absorbed.
Refraction: direction change of light through transparent media with different optical density Dispersion: separation of light into its constituent wavelengths Refractive index: the light-bending ability of a medium |
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Describe a major operational difference between Compound and Simple Microscopes.
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Simple microscopes have a single lens
Compound has two or more lenses |
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Define resolving power of a microscope, and magnification.
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Resolving power: maximum resolution. Eg. A microscope with a resolving power of 0.4 nm can distinguish between two points ≥ 0.4 nm.
Magnification: enlargement of image |
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Match the descriptions below with either A. more or B. less.
Shorter wavelengths of light provide _____ resolution A microscope with a blue filter will transmit _____ wavelengths of light to the ocular Immersion oil is used for high power objectives because it bends light _____ Infinity optics allows _____ movement of the microscope stage Higher numerical aperture equates to a _____ visual working distance |
More
Less Less Less Less Less |
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State two major functions of a microscope condenser.
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Gathers light from the field diaphragm and focuses light onto the specimen
fills the numerical aperture (NA) of objective (must match the NA) |
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State whether high or low magnification is used with high NA objectives.
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High
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State the two most important elements of optical systems for quality detailed imaging.
Identify three types of compound microscopes. |
Bright-field: uses direct visible light (specimen requires staining)
Dark-field: uses indirect visible light (reflected light), specimen does not require staining. Phase contrast: uses refracted and diffracted rays of visible light (specimen does not require staining). |
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Discuss the utility of oil for the examination of specimens under high power.
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Oil immersion improves the resolution of light microscopes. It capture refracted light and concentrates it through the specimen.
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Name the chemical agent that should be used to clean an objective lens after it has been used with oil immersion.
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Xylene
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