A pollen grain was viewed with a microscope using ×500 magnification. The image size of the pollen grain was measured as 75mm. Which calculation would give the actual size of the pollen grain in millimetres?
A) \(\frac{75}{500}\)
B) \(\frac{500}{75}\)
C) \( \frac{75\times 1000}{500}\)
D) \( \frac{500}{75\times 1000}\)
▶️ Answer/Explanation
Ans: A
The actual size of an object under a microscope is calculated using the formula:
\[ \text{Actual Size} = \frac{\text{Image Size}}{\text{Magnification}} \]
Given the image size is \(75\,mm\) and magnification is \(500\), the actual size is:
\[ \frac{75}{500} \]
Thus, the correct answer is A.
The diagram shows a fly.
The line XY represents the length of the wing. The length of line XY is 26mm. The actual size of the wing between X and Y is 4mm. What is the magnification of the diagram?
A) ×0.15
B) ×6.5
C) ×22
D) ×104
▶️ Answer/Explanation
Ans: B
Magnification is calculated using the formula:
\[ \text{Magnification} = \frac{\text{Size of Image}}{\text{Actual Size}} \]
Here, the image size (XY) is 26 mm, and the actual wing size is 4 mm. Plugging in the values:
\[ \text{Magnification} = \frac{26\, \text{mm}}{4\, \text{mm}} = 6.5 \]
Thus, the correct answer is B (×6.5).