MICROSCOPES

STEREO STEREO COMPOUND LIGHTCOMPOUND LIGHT TRANSMISSION ELECTRON (TEM)TRANSMISSION ELECTRON (TEM) SCANNING ELECTRON (SEM)SCANNING ELECTRON (SEM)

IMPORTANT TERMS

RESOLUTION- the ability to distinguish RESOLUTION- the ability to distinguish small, close objects, or to see things small, close objects, or to see things clearlyclearly

Human eye- sees 2 lines 1 mm apart at Human eye- sees 2 lines 1 mm apart at a distance of 5.15 m a distance of 5.15 m

MAGNIFICATION- ability to make an MAGNIFICATION- ability to make an image appear largerimage appear larger

STEREO (Dissecting) MICROSCOPE Useful for dissectionsUseful for dissections Magnification up to 10 XMagnification up to 10 X

COMPOUND LIGHT MICROSCOPE Uses 2 lenses(Hence Compound)Uses 2 lenses(Hence Compound) Light bulb or mirror is light sourceLight bulb or mirror is light source To find total magnification, multiply To find total magnification, multiply

magnifications of 2 lenses in usemagnifications of 2 lenses in use EX- eyepiece is 10 X and low power EX- eyepiece is 10 X and low power

objective lens is 4 X, total magnification objective lens is 4 X, total magnification is 10 X 4 or 40 Xis 10 X 4 or 40 X

COMPOUND LIGHT MICROSCOPE Usually limited to 1000 X total Usually limited to 1000 X total

magnification - because it uses lightmagnification - because it uses light Can study living or dead specimensCan study living or dead specimens Bacteria are the smallest living Bacteria are the smallest living

specimen that can be viewedspecimen that can be viewed

Compound Light Micrograph

TRANSMISSION ELECTRON MICROSCOPE (TEM) Uses electrons to magnify specimensUses electrons to magnify specimens Electrons pass through the specimenElectrons pass through the specimen Specimens must be sliced very thinly- Specimens must be sliced very thinly-

therefore they’re deadtherefore they’re dead Specimens appear darkSpecimens appear dark Total magnification can be 1-2 million XTotal magnification can be 1-2 million X

TEM Micrograph

SCANNING ELECTRON MICROSCOPE Scans surface of 3D objects using Scans surface of 3D objects using

electronselectrons Specimens are deadSpecimens are dead Specimens coated with a metal- picture Specimens coated with a metal- picture

appears metallicappears metallic Can see depthCan see depth Total magnification = 300,000 XTotal magnification = 300,000 X

SEM Micrograph