You calculate a microscope by determining the total magnification and then using it to find the actual size of a viewed object.
Understanding Microscope Calculations
Microscope calculations typically involve two key concepts: total magnification and actual size.
1. Determining Total Magnification
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Eyepiece Lens Magnification: Microscopes have an eyepiece lens, often with a magnification of 10x.
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Objective Lens Magnification: Different objective lenses offer varying magnifications, such as 4x, 10x, or 40x.
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Total Magnification Formula: The total magnification is calculated by multiplying the eyepiece lens magnification by the objective lens magnification being used.
- Formula: Total Magnification = Eyepiece Lens Magnification × Objective Lens Magnification
- Example: A 10x eyepiece lens with a 40x objective lens has a total magnification of 400x (10 x 40 = 400).
2. Calculating Actual Size
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Image Size: The size of the image that you see is measured using a graticule or an eyepiece ruler.
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Actual Size Calculation To find the actual size of the object, you must divide the image size by the total magnification.
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Formula: Actual Size = Image Size / Total Magnification
- Example: If the image size measures 6.6 units on the graticule, and the total magnification is 400x, the actual size would be 6.6/400.
- This means that the actual size is 0.0165 units (the units will depend on the graticule). The measurement would likely need to be converted to micrometers or millimeters.
Reference Information
According to the reference:
- A particular microscope with a 10x eyepiece and a 40x objective lens has a total magnification of 400x.
- If an image size is 6.6 units, the actual size is found by dividing the image size (6.6) by the total magnification (400), therefore, actual size = 6.6/400.
Practical Insights
- Units of Measurement: Ensure that you are using consistent units. If the image size is measured in millimeters, your final answer for the actual size will also be in millimeters.
- Graticule Calibration: Each microscope should have its graticule calibrated so that the units on the graticule can be converted into the true unit of length.
- Changing Magnifications: The total magnification changes each time the objective lens is changed. Thus, it is important to perform the calculation with the new magnification.
