microscope required practical DEFINITELY IN EXAM

Question 1

required practical microscopes

what is the purpose of the:

1. stage
2. clips on the stage
3. lamp
4. mirror (if don’t have a lamp)
5. objective lenses
6. eyepiece
7. coarse focusing knob + fine focusing knob
8. coarse
9. fine

Answer 1

1. the stage is where we place the microscope slide to see the cells
2. clips hold the slide in place
3. light from the lamp passes up through the microscope slide allowing you to see a clear image
4. mirror is used to reflect light up through the microscope slide onto the specimen
5. objective lenses have 3 different magnification strengths (4x, 10x, 40x )
6. the eyepiece is where we look through and contains the eyepiece lens which has a magnification of 10x
7. coarse focusing knob + fine focusing knob allows you to see the specimen more clearly
8. coarse = lower magnification - shorter lens
9. fine = higher magnification- longer lens

Question 2

how to use a optical microscope to view a sample

Answer 2

place the sample on the stage
use the clips to hold the slide in place
select lowest power objective lens (typically 4x)
position the objective lens so it almost touches the microscope slide
slowly turn the coarse focusing dial
(make sure to look from the side while adjusting the position of the objective lens because if looking through the eyepiece there is a risk we will damage the slide)
look down through the eyepiece coarse focusing dial increases the distance between objective lens and the slide until the cells come into focus
use the fine focusing dial to bring the cells into a clear focus
adjust the fine focusing dial to bring the cells back into focus

Question 3

how do you find the total magnification

Answer 3

magnification of eyepiece lens x magnification of objective lens

Question 4

what is the magnification of the eyepiece lens always

Answer 4

10x

Question 5

what do you measure the diameter of the field of view on the stage in by using a plastic ruler

Answer 5

millimetres
(using a scale bar)
also when drawing magnification diagrams should include the magnification

Question 6

define resolution

Answer 6

ability to distinguish between 2 points on an image

e.g : amount of detail

Question 7

what are the benefits of an electron microscope

Answer 7

• higher resolution
• higher magnification

but expensive + monochromatic (when a light microscope has colour)

Question 8

define magnification

Answer 8

How many times larger the image is than the object

Question 9

Convert 23 mm to nm

Answer 9

23mm x 1000 = 23000 μm

23000 μm x 1000 = 23000000 nm

2.3 x 10 to the power of 7 nm