Exam 1

Question 1

Convex lenses can also be called

Answer 1

Positive lenses

Question 2

Concave lenses can also be called

Answer 2

Negative lenses

Question 3

Concave lenses can be used to help correct for

Answer 3

Abberations

Question 4

The conjugate foci of a lens are the

Answer 4

Object and its image

Question 5

Real image vs. virtual image

Answer 5

A real image can be formed/visualized on a screen or film. A virtual image can only be seen by looking through the lens

Question 6

What would you adjust on a microscope to reduce glare?

Answer 6

Condenser aperture

Question 7

Resolution formula

Answer 7

R = wavelength
_________
2 x NA (Numerical aperture)

Question 8

Working distance

Answer 8

The distance from the specimen to the objective lens

Question 9

The range in which an object is in focus

Answer 9

Depth of field

Question 10

The distance from the specimen to the objective lens

Answer 10

Working distance

Question 11

Focal length and working distance of a higher magnification lens

Answer 11

Smaller focal length and working distance

Question 12

The location of an object if the image is real, smaller, and inverted

Answer 12

Greater than 2F

Question 13

The location of an object if the image is real, the same size, and inverted

Answer 13

Located at 2F

Question 14

The location of an object if the image is real, magnified, and inverted

Answer 14

Between 2F and 1F

Question 15

The location of an object if the image is virtual, magnified, and erect

Answer 15

Less than 1F

Question 16

Why does chromatic aberration occur?

Answer 16

Shorter wavelengths are refracted more than longer wavelengths

Question 17

Why does spherical aberration occur?

Answer 17

Light passing through the centre of the lens does not bend as much as those rays passing through the periphery

Question 18

Three types of objectives with correction for chromatic aberration are:

Answer 18

Achromats, semi-apochromats, and apochromats

Question 19

Lenses that are corrected for spherical aberration have the designation:

Answer 19

plan

Question 20

Which microscope component focuses light on the specimen

Answer 20

Condenser assembly

Question 21

Which microscope component controls the size of the cone of light striking the specimen

Answer 21

Condenser aperture diaphragm

Question 22

The distance from the optical centre of the objective lens to the focal plane of the ocular

Answer 22

Optical tube length

Question 23

Optical tube length

Answer 23

The distance from the optical centre of the objective lens to the focal plane of the ocular

Question 24

The distance from the top of the ocular to the objective/nosepiece junction

Answer 24

Mechanical tube length

Question 25

Mechanical tube length

Answer 25

The distance from the top of the ocular to the objective/nosepiece junction

Question 26

Hygenian and Ramsden are types of:

Answer 26

Oculars

Question 27

Abbe and Aplanatic-achromatic are types of:

Answer 27

Condenser

Question 28

What does the amount of refraction depend on?

Answer 28

Angle of incidence and refractive index of mediums

Question 29

Light entering a more dense medium bends ______ normal

Answer 29

towards

Question 30

Light entering a less dense medium bends ______ normal

Answer 30

away from

Question 31

When a light ray attempts to leave a dense medium, if the angle of incidence is greater than the _________, then the light ray will be reflected

Answer 31

critical angle

Question 32

How can refractive index be calculated?

Answer 32

RI (n) = speed of light in a vacuum (air) / speed of light in a medium OR Snell's Law (RI = sin angle of incidence / sin angle of refraction)

Question 33

Snell's Law

Answer 33

RI = sin angle of incidence / sin angle of refraction

Question 34

Refractive index can be expressed as:

Answer 34

RI or n

Question 35

Refractive index of air

Answer 35

1.00

Question 36

Refractive index of crown glass

Answer 36

1.52

Question 37

What two factors is resolution dependent upon?

Answer 37

Wavelength of light used and the numerical aperture

Question 38

Numerical aperture

Answer 38

Mathematical expression of the light gathering ability of a lens

Question 39

3 disadvantages to high numerical aperture lenses

Answer 39

Decreased working distance Decreased depth of field Decreased flatness of field

Question 40

Numerical aperture can be calculated as:

Answer 40

N.A = n sin u

Question 41

Useful magnification occurs when:

Answer 41

1000 x N.A > total magnification

Question 42

What does Kohler illumination do?

Answer 42

Produces even illumination of the specimen, and helps to match the numerical aperture of the condenser to the objective lens

Question 43

In order to set Kohler, a microscope must have which components?

Answer 43

Radiant field diaphragm and collector lens, condenser assembly with an adjustable aperture diaphragm

Question 44

An infinity corrected lens must be used with which type of microscope

Answer 44

A microscope that has a tube lens

Question 45

Angle of incidence

Answer 45

The angle formed by the light entering an object compared to normal (a line drawn at a 90 degree angle to the surface)

Question 46

Angle of reflection

Answer 46

The angle formed by light reflected from a surface compared to normal (a line drawn at a 90 degree angle to the surface)

Question 47

Angle of refraction

Answer 47

The angle formed by the light leaving an object compared to normal (a line drawn at a 90 degree angle to the surface)

Question 48

Critical angle

Answer 48

The angle at which light is unable to leave a more dense medium for a less dense medium

Question 49

Visible light spectrum

Answer 49

about 400-700nm

Question 50

Empty magnification occurs when:

Answer 50

1000 x N.A