Microscopes

Question 1

Optical (light) microscopes

Answer 1

Used to look at whole cells or tissues and view large structures within the cell. Maximum resolution being 0.2 micrometers, maximum magnification is x1500

Question 2

Transmission electron microscope (TEM)

Answer 2

Able to see a range of organelles. Use electromagnetic to focus a beam of electrons to illuminate the specimen, provides greater magnification and higher resolution.

Question 3

Scanning electron microscope (SEM)

Answer 3

Used to view the surfaces of solid objects, elections are reflected off the surface and creates an electrical signal displayed on a computer • lower magnification than TEM and lower resolution

Question 4

Resolution

Answer 4

The ability to distinguish between two points that are close together

Question 5

Resolution factors

Answer 5

The wavelength of the Em radiation being used to view the object, the refractive index of the imaging medium (air or oil), the angular aperture of the objective lens.

Question 6

Electronvolt (eV)

Answer 6

The measure of the amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum

Question 7

Angular aperture (A)

Answer 7

In theory the maximum A of an objective lens is 180° in practical its 144°. When calculating resolution, the angle is halved and its sine value is calculated