Transmission Electron Microscope (TEM)

-very expensive with 2 million times magnification

– specimen must be cut very thinly and must be dead

Scanning Electron Microscope (SEM)

– produces a 3-D image of the surface

– whole specimen must be dead

Compound Microscope – the one we use

– two lenses illuminated by a light source

– specimen can be alive or dead

MAGNIFICATION: how many times bigger an object seems

RESOLUTION: How much detail can be seen

FIELD OF VIEW: Circular area you see illuminated

MICROSCOPE CALCULATIONS:

Allows a biologist to determine the actual size of specimen

1. TOTAL MAGNIFICATION (MAG)

Two lenses: Ocular   __________

Objective lenses:  Low_______  Med_______   High_______

Total MAG = MAG of ocular  x MAG of objective

Objective low med high
Ocular
Objective
Total MAG

2. FIELD OF VIEW (FOV)

– As magnification increases the FOV decreases

– essential you are blowing up part of the FOV

– FOV can be measured with a ruler on low power and calculated for medium and high powers

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