Physics June 2010 paper, Q3- resolution

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joyoustele
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How do I do this? I looked at the mark scheme but dont understand it, Attachment 721290
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uberteknik
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(Original post by joyoustele)
How do I do this? I looked at the mark scheme but dont understand it, Attachment 721290
What exam board, which paper?
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joyoustele
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(Original post by uberteknik)
What exam board, which paper?
OCR PHYSICS B, Q3

Markscheme: http://www.ocr.org.uk/Images/65276-m...ction-june.pdf (Q3)
http://www.ocr.org.uk/Images/58054-q...-in-action.pdf
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uberteknik
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Measure the height or width of the image in cm. Do the same for the diameter of the Sun.

The march scheme measured the height as approximately 8.25cm and the Sun's diameter as 4.5cm. (Your screen scale may differ, the key is to make sure you get the ratio of the image height or width to the sun's diameter using the same scale)

The image height is 710 pixels so the diameter of the sun in pixels is the fraction \frac{4.5}{8.25} \text{ x 710} = 387 pixels rounded up to 390.

Finally divide the diameter of the sun in km, by the number of pixels to give the resolution of the image in km/pixel.

NB As long as the method is clearly stated and the answer is stated to within +/-400km/pixel, full marks are awarded.
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joyoustele
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(Original post by uberteknik)
Measure the height or width of the image in cm. Do the same for the diameter of the Sun.

The march scheme measured the height as 8.25cm and the Sun's diameter as 4.5cm.

The image height is 710 pixels so the diameter of the sun in pixels is the fraction \frac{4.5}{8.25} \text{ x 710} = 387 pixels rounded up to 390.

Finally divide the diameter of the sun in km, by the number of pixels to give the resolution of the image in km/pixel.

NB As long as the method is clearly stated and the answer is stated to within +/-400km/pixel, full marks are awarded.
The bit I dont get is why 4.5 is divided by 8.25....
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uberteknik
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(Original post by joyoustele)
The bit I dont get is why 4.5 is divided by 8.25....

710 pixels = 8.25cm total image field of view height, as measured when printed on an A4 sized exam paper.

4.5cm is the diameter of the sun measured to the same scale.
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joyoustele
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(Original post by uberteknik)
710 pixels = 8.25cm total image field of view height, as measured when printed on an A4 sized exam paper.

4.5cm is the diameter of the sun measured to the same scale.
nm I get it now.. Thanks
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