Let’s solve each problem step by step. We’ll use the formula:
Magnification = Image size ÷ Actual size
And remember to convert units when needed — especially between millimeters (mm) and micrometers (µm).
We know:
1 mm = 1000 µm
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Problem 1:
> The length of the drawing of a worm is shown on the diagram. The actual length of the worm is 10mm. Calculate the magnification of the drawing.
From the diagram, the image size (drawing) is labeled as
50 mm.
Actual size = 10 mm
So,
Magnification = 50 mm ÷ 10 mm =
5
✔ Answer:
x5
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Problem 2:
> A student makes a drawing of an onion cell, the width of the cell drawn is 110mm. The actual width of the cell is 250µm. Calculate the magnification of the drawing.
Image size = 110 mm
Actual size = 250 µm → we need to convert this to mm so units match.
Since 1 mm = 1000 µm, then:
250 µm = 250 ÷ 1000 =
0.25 mm
Now calculate:
Magnification = 110 mm ÷ 0.25 mm =
440
✔ Answer:
x440
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Problem 3:
> A student draws a diagram of a mitochondrion. The diagram has a magnification of x15000. The diagram is 75mm long. What is the actual size of the mitochondrion, in µm?
We rearrange the formula:
Actual size = Image size ÷ Magnification
Image size = 75 mm
Magnification = 15000
Actual size = 75 ÷ 15000 =
0.005 mm
But the question asks for the answer in
micrometers (µm).
Convert 0.005 mm to µm:
0.005 mm × 1000 =
5 µm
✔ Answer:
5 µm
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Problem 4:
> A student draws a diagram of a cheek cell with a width of 40mm. The actual width of the cell is 25 µm. What is the magnification of the drawing?
Image size = 40 mm
Actual size = 25 µm → convert to mm first.
25 µm = 25 ÷ 1000 =
0.025 mm
Magnification = 40 ÷ 0.025 =
1600
✔ Answer:
x1600
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Bonus: Rearranging the Formula
Original:
Magnification = Image size ÷ Actual size
Rearranged:
-
Actual size = Image size ÷ Magnification
-
Image size = Magnification × Actual size
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Converting Units Practice:
#### Convert into micrometers (multiply mm by 1000):
1. 3 mm = 3 × 1000 =
3000 µm
2. 0.2 mm = 0.2 × 1000 =
200 µm
3. 0.008 mm = 0.008 × 1000 =
8 µm
#### Convert into millimeters (divide µm by 1000):
1. 1.5 µm = 1.5 ÷ 1000 =
0.0015 mm
2. 0.5 µm = 0.5 ÷ 1000 =
0.0005 mm
3. 37.5 µm = 37.5 ÷ 1000 =
0.0375 mm
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Final Answer:
Problem 1: x5
Problem 2: x440
Problem 3: 5 µm
Problem 4: x1600
Unit conversions:
Into µm: 3000, 200, 8
Into mm: 0.0015, 0.0005, 0.0375
Parent Tip: Review the logic above to help your child master the concept of microscope magnification worksheet.
