2.2 Magnification And Calibration

Question 1

Define magnification

Answer 1

How much bigger the image is than the specimen

Question 2

Formula to calculate magnification

Answer 2

Magnification = image size/ actual size

Question 3

How to covert from mm to micrometer to nanometre

Answer 3

• mm to micrometre multiple by 1000

- micrometre to nanometre multiple by 1000

Question 4

Define resolution

Answer 4

Resolution is how well a microscope distinguishes between two points that are close together.

Therefore resolution is how detailed the image is

Question 5

What is an eyepiece graticule, what is it used for?

Answer 5

• used to measure size of a sample under a microscope
• it is a glass disc marked with a fine scale of 1 to 100 (no units) and remains unchanged whichever objective lens is in place but the relative size of the divisions change
• the scale on the graticule at each magnification needs to b calibrated using a stage micrometer (to see how many micrometers divisions represent)

Question 6

What is a stage micrometer?

Answer 6

Is a microscope slide with a very accurate scale in micrometers engraved on it.

The scale on the micrometer slide is usually:

100 divisions= 1mm so 1 divisions= 10 micrometers

You calibrate the eyepiece graticule, using the stage micrometer, for each lens separately. Once all three lenses are calibrated you can measure he same cell using the different lenses and can get the actual measurements.

Question 7

Explain how light diffraction limits resolution

Answer 7

Diffraction happens when light passes through structures
Light waves spread out and overlap
Individual objects do not appear separate and the image comes out blurry