2.2

Question 1

Why do electron microscopes have a vacuum in them? (1)

Answer 1

(1) to PREVENT the air from ABSORBING the electrons in the beam

Question 2

Why do electron microscopes have a high resolution? (1)

Answer 2

(1) because the ELECTRON BEAM has a VERY SHORT WAVELENGTH.

Question 3

What are the 2 types of electron microscopes? (2)

Answer 3

(1) transmission electron microscope (TEM)
(2) scanning electron microscope (SEM)

Question 4

What are the advantage of TEM? (1)

Answer 4

(1) highest resolution out of a normal electron microscope & SEM & optical

Question 5

What are the As of SEM? (3)

Answer 5

(1) the specimen DOESNT have to be extremely THIN
(2) the image produced is 3D
(3) resolving power is higher than optical microscopes

Question 6

What are the DAs of SEM? (5)

Answer 6

(1) lower resolving power than TEM (20 nm)
(2) living specimens can’t be observed (vacuum conditions)
(3) a complex ‘staining’ process is required
(4) the image is black and white
(5) the image may contain ARTEFACTS, so you may not know what you’re looking at in the micrograph

Question 7

What are the DAs of TEM? (6)

Answer 7

(1) living specimens can’t be observed (vacuum conditions)
(2) a complex ‘staining’ process is required
(3) the image is 2D
(4) the image is black and white
(5) the specimen has to be EXTREMELY THIN
(6) the image may contain ARTEFACTS, so you may not know what you’re looking at in the micrograph