the electron microscope

Question 1

what is magnification

Answer 1

how many times bigger the image size is than the actual specimen

Question 2

describe some limitations of TEM

Answer 2

no living specimens can be observed, complex staining process- black and white image, image may contain artefacts, specimin must be extemly thin, 2D image

Question 3

describe some limitations of SEM

Answer 3

same limitations of TEM except specimens don’t need to be as thin, lower resolving power than TEM, around 20nm, still 10X bigger than light microscopes

Question 4

describe how the transmission electron microscope works

Answer 4

electron gun produces a beam of electrons that is focused onto the specimen by a condenser electromagnet

Question 5

describe how the scanning electron microscope works

Answer 5

directs beam of electrons onto the surface of specimen from above, electrons are scattered by the specimen- pattern of this scattering depends on the contouring of the specimen surface

Question 6

give some similarities and differences of light and electron microscopes

Answer 6

electron microscopes are in a vacuum, light microscopes are not, electron microscopes have a higher magnification + resolution

Question 7

what are the differences in how specimens are seen in light/ electron microscopes

Answer 7

light goes through the specimen in light microscopes but a beam of electrons is fired at the surface of the specimen in electron microscopes, it does not go through