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Size of SpecimensCambridge IGCSE Biology: Flashcards

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What is the formula used to calculate magnification?

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What is the formula used to calculate magnification?
Magnification = Image size ÷ Actual size
Define magnification.
Magnification is the number of times larger an image appears compared to the actual size of the specimen.
If a specimen has an actual size of 2 mm and appears as 20 mm under magnification, what is the magnification?
Magnification = 20 mm ÷ 2 mm = ×10 (or 10× magnification)
What unit is typically used to measure biological specimens in calculations?
Millimetres (mm) are typically used to measure biological specimens in magnification calculations.
Convert 1 mm into micrometres.
1 mm = 1000 μm (micrometres)
Convert 5000 μm into millimetres.
5000 μm = 5 mm
How many micrometres are in 0.5 mm?
0.5 mm = 500 μm
Rearrange the magnification formula to find actual size.
Actual size = Image size ÷ Magnification
An image of a cell measures 15 mm under ×150 magnification. What is the actual size of the cell?
Actual size = 15 mm ÷ 150 = 0.1 mm (or 100 μm)
Rearrange the magnification formula to find image size.
Image size = Magnification × Actual size
A specimen has an actual size of 0.02 mm and is viewed under ×500 magnification. What is the image size?
Image size = 500 × 0.02 mm = 10 mm
Convert 250 μm into millimetres.
250 μm = 0.25 mm
What is the conversion factor between millimetres and micrometres?
1 mm = 1000 μm (multiply mm by 1000 to get μm; divide μm by 1000 to get mm)
A biological specimen measures 0.005 mm. Express this measurement in micrometres.
0.005 mm = 5 μm
If an image appears 8 times larger than the actual specimen, what is the magnification?
The magnification is ×8