1. Magnification

2. Magnification Photomicrographs often have magnification bars to allow
calculation of the actual size of specimens.
4.55μm

3. Magnification
In this exercise you will calculate the
magnification and/or true size of the
following: 1 2 3 4 5 8 6 7 10 9

4. Before we begin:
Note:
Numbers written like this: 1.26 x 105 mean you move the decimal point to the right. In this case you move it 5 times:
1.26 x 105 = .

5. Before we begin:
Note:
Numbers written like this: 1.26 x 10-5 mean you move the decimal point to the left. In this case you move it 5 times:
1.26 x 10-5 =

6. Have a go at these: 14500.0 1.45 x 104 = 0.37 x 107 = 86.41 x 10-3 =
0.0265

7. Figure 5.1 Paramecium caudatum
x600

8. Figure 5.1 Paramecium caudatum
Measured length = 142mm
142 ÷ 600 = 0.237mm
0.237mm = 237μm
x600

9. Figure chloroplasts
x9000

10. Figure chloroplasts
Mean measured length of the four largest chloroplasts = 39.25mm
39.25 ÷ 9000 = mm
0.0044mm = 4.4μm
x9000

11. Figure 5.3 a bacterium Measured length = 128mm
128 ÷ 0.002mm = magnification
Magnification = x64000

12. Figure 5.4 seven week human embryo

13. Figure 5.4 seven week human embryo
Measure the actual length of the scale bar and divide by the length it represents
Magnification = 25 ÷ 10 = x2.5

14. Figure 5.5 head of a fruit fly

15. Figure 5.5 head of a fruit fly
Measure the actual length of the scale bar and divide by the length it represents
Magnification = 12.5 ÷ 0.2 = x62.5

16. Figure pollen grain

17. Figure pollen grain
(a) Measure the actual length of the scale bar and divide by the length it represents
Magnification = 25 ÷ 0.02 = x1250
(b) 47mm
(c) 47 ÷ 1250 = mm
0.0376mm = 37.6μm

18. Figure 5.7 red blood cells in an arteriole

19. Figure 5.7 red blood cells in an arteriole
Measured length of scale bar = 30mm
Magnification = 30 ÷ 0.01 = x3000
Diameter = 25mm [approx]
Actual diameter = 25 ÷ 3000 = mm
0.0083mm = 8.3μm

20. Figure 5.8 a mitochondrion

21. Figure 5.8 a mitochondrion
Measured length of scale bar = 30mm
Magnification = 30 ÷ = x15000
Measured width = 34mm
Actual width = 34 ÷ = mm
0.0023mm = 2.3μm

22. Figure 5.9 bacteriophage [a type of virus]

23. Figure 5.9 bacteriophage [a type of virus]
Measured length of phage = 29mm
Magnification = 29 ÷ =
Magnification = 1.45 x 105

24. Figure potato cells
starch grains

25. Figure 5.10 potato cells Mean diameter of the cells = 38mm [approx]
Measured length of scale bar = 24mm
Magnification = 24 ÷ 0.1 = x240
Diameter of the cells = 38 ÷ 240 = 0.158mm
0.158mm = 158μm

26. Magnification
The resolving power of the unaided eye is approximately 0.1mm
The maximum useful magnification of light microscope is around x1500
Plant and animal cells typically measure around 20µm
Many organelles are as small as 25nm – beyond the resolving power of the light microscope [wavelength of light is 500nm approx]
Wavelength of electron beam is 0.005nm
Maximum resolving power of the electron microscope is 0.2nm

27. Question 11 bacteriophage 0.2μm bacterium 2.0μm mitochondrion 2.3μm
Structure
Size
Kind of structure
Visible at x1500?
bacteriophage
0.2μm
virus 
bacterium
2.0μm
prokaryotic cell
 (just)
mitochondrion
2.3μm
eukaryotic organelle 
chloroplast
4.4μm
red blood cell
8.3μm
eukaryotic cell
pollen grain
38μm
potato cell
158μm
paramecium
237μm
eukaryotic organism
embryo
30mm