tammie94
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actual size = Image size / magnification
When would you use this equation and how does this differ from calibration. How would you know what the image size is and wouldn't it be more efficient to just calibrate what one eye piece unit is worth.

Can I also ask what the book means by the ruler is 1mm long as it doesn't specify whether it's talking about the eye piece graticule or the stage micrometer.

There's also 2 examples in my book:
with a *4 objective lens and *10 eye piece (magnificatiion = *40), 40 epu (eye piece units) = 1mm (1000 micrometers). Therefore 1 epu = 1000/40 = 25 micrometers.
with a *10 objective lens (total magnification = *100), 100 epu = 1000 micrometers. So 1 epu = 10 micrometers.

If they are refering to the micrometer being 1mm long then why do we even use the eye piece graticule and vice versa. Please help me to understand. My text book is so indirect and unclear!
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Pride
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(Original post by tammie94)
actual size = Image size / magnification
When would you use this equation and how does this differ from calibration. How would you know what the image size is and wouldn't it be more efficient to just calibrate what one eye piece unit is worth.

Can I also ask what the book means by the ruler is 1mm long as it doesn't specify whether it's talking about the eye piece graticule or the stage micrometer.

There's also 2 examples in my book:
with a *4 objective lens and *10 eye piece (magnificatiion = *40), 40 epu (eye piece units) = 1mm (1000 micrometers). Therefore 1 epu = 1000/40 = 25 micrometers.
with a *10 objective lens (total magnification = *100), 100 epu = 1000 micrometers. So 1 epu = 10 micrometers.

If they are refering to the micrometer being 1mm long then why do we even use the eye piece graticule and vice versa. Please help me to understand. My text book is so indirect and unclear!
Ahh that sounds like the OCR textbook.

Well, you might use the M = I divided by A equation when you're given the actual size of a cell and you are given the size of the image, then to find magnification, you'd divide the image size by the actual size given. You might have to re-arrange the equation for some questions.

On the other hand, about the stage micrometer, it's 1mm long (1000 micrometres), and it's divided into 100 divisions so each division is 10 micrometres long or 0.01mm. Then with a x4 objective and x10 eyepiece, the magnification'd be x40 because you do 4*10, so 40 eyepiece units would equal 1mm.

40epu = 1000 micrometres
1epu = 1000/40 = 25 micrometres.

so if you were to put another object on the stage, you'd be able to tell that if it was 2 units in width for example it'd be 50micrometres.
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tammie94
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(Original post by Pride)
Ahh that sounds like the OCR textbook.

Well, you might use the M = I divided by A equation when you're given the actual size of a cell and you are given the size of the image, then to find magnification, you'd divide the image size by the actual size given. You might have to re-arrange the equation for some questions.

On the other hand, about the stage micrometer, it's 1mm long (1000 micrometres), and it's divided into 100 divisions so each division is 10 micrometres long or 0.01mm. Then with a x4 objective and x10 eyepiece, the magnification'd be x40 because you do 4*10, so 40 eyepiece units would equal 1mm.

40epu = 1000 micrometres
1epu = 1000/40 = 25 micrometres.

so if you were to put another object on the stage, you'd be able to tell that if it was 2 units in width for example it'd be 50micrometres.
Thank you so much and yep you're right. OCR text books can be so unclear sometimes.
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Pride
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(Original post by tammie94)
Thank you so much and yep you're right. OCR text books can be so unclear sometimes.
ahh glad that's helped
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NerdFighteria
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(Original post by Pride)

On the other hand, about the stage micrometer, it's 1mm long (1000 micrometres), and it's divided into 100 divisions so each division is 10 micrometres long or 0.01mm. Then with a x4 objective and x10 eyepiece, the magnification'd be x40 because you do 4*10, so 40 eyepiece units would equal 1mm.

40epu = 1000 micrometres
1epu = 1000/40 = 25 micrometres.

so if you were to put another object on the stage, you'd be able to tell that if it was 2 units in width for example it'd be 50micrometres.
how do you convert EPU into micrometers? I'm so confused and have homework in for lunch tomorow :/ I can understand the rest of it it's just that. Any help would be GREATLY appreciated :confused::confused:
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Pride
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(Original post by NerdFighteria)
how do you convert EPU into micrometers? I'm so confused and have homework in for lunch tomorow :/ I can understand the rest of it it's just that. Any help would be GREATLY appreciated :confused::confused:
I know it's confusing. 1 mm = 1000 micrometres, um

Now, the epu depends on your magnification.
At x40 (x4 and x10) you know 1000 micrometres would be 40epu.

at x100, 1000 micrometres would be 100epu
1 epu would be 10 micrometres.

The set measurement is 1mm, that is used to help you calibrate. Epu varies on magnification
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NerdFighteria
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(Original post by Pride)
I know it's confusing. 1 mm = 1000 micrometres, um

Now, the epu depends on your magnification.
At x40 (x4 and x10) you know 1000 micrometres would be 40epu.

at x100, 1000 micrometres would be 100epu
1 epu would be 10 micrometres.

The set measurement is 1mm, that is used to help you calibrate. Epu varies on magnification
Thank you so much!! this really helped me out
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RedDots
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Can Anyone help me about how microscope calculation?

If an object has a diameter of 17 graticule units with the x40 objective, what is its actual diameter in microns?
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e4i8rijerh
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My ocr text book says that with each increasese in magnification the relative size of the divisions increases for eyepiece graticule but should not the relative size of divisions for the eyepiece graticule decrease for each increase in magnification as each division would be worth less as the image is magnified.
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