magnification lesson of gcse, how to find magnification questions

magnification lesson of gcse, how to find magnification questions

1. Magnification & Resolution Magnification is the making of the appearance of an object to increase. Resolution is the ability to distinguish between two separate points. This referred as the resolving power of a microscope.

2. Light Microscope Uses a beam of light to observe the sample; Can magnify objects to approximately 2000 (two thousand) times; Has a resolution of approximately 200 nm (nanometres).

3. Electron Microscope Uses a beam of electrons to observe the sample; Can magnify objects to approximately 2,000,000 (two million) times; Has a resolution of approximately 0.1nm (nanometres).

4. Onion Cell Light Microscope Electron Microscope Magnification up to 2000 times; Resolution 200 nm. Magnification up to 2,000,000 times; Resolution 0.1 nm. Question: Why can you only see the organelles of the onion cell by using an electron microscope?

5. Conversion Table: mm to ɥm Length in mm Length in ɥm 1 1000 0.1 100 0.01 10 0.001 1

6. How big? The animation showed different scales of measurement: 1cm = 10mm 1mm = 1000µm ( micrometers ) How many µm in 1cm?

7. Worked Example: Find the actual diameter of a bacteria cell Image size: Magnification: X5000 Actual size: ɥm The equation to use is…. Actual Size = Image size (mm) Magnification Step 1. Magnification = 5000 Step 2. Count the size of the bacteria (mm) – 10mm. Step 3. Do the calculation = 10 ÷ 5000 Step 4: 10 ÷ 5000 = 0.002mm Step 5: Convert mm into ɥm using the table 0.001mm = 1ɥm so 0.002mm must be 2 ɥm. ANSWER = Size of bacteria is 2 ɥm

8. Find the diameter of the plant cell. Actual size = image size ÷ magnification .

9. Object Image Size Actual size Magnification E Coli 20mm 0.002mm x Yeast Cell 10mm 0.006mm x Blood cell 300mm 0.01mm x Pollen Grain 40mm 0.5mm x Hair 6cm 3.5cm x Object Image Size Actual size Magnification Salmonella 1.5cm 0.003mm x Crystal 3cm 0.05mm x White Cell 20mm 20 µ m x Dust 25mm 0.1cm x Finger Nail 5mm 1.5cm x Easier – Same units of measurement Difficult – Different units of measurement 20 ÷ 0.002 = x10,000 10 ÷ 0.006 = x1,666.67 300 ÷ 0.01 = x30,000 40 ÷ 0.5 = x80 6 ÷ 3.5 = x1.7 15mm ÷ 0.003mm = x50 30mm ÷ 0.05mm = x600 20,000µ ÷ 20 20µ m = x1000 25mm ÷ 20 1mm m = x25 5mm ÷ 20 15mm m = x0.3