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# Practical Skills Question watch

1. Hi all,

Hope you are doing fine. I was doing the AS Physics 2014 specimen paper and I couldn't do this question.

'A student has a diffraction grating that is marked 3.5 × 10^3 lines per m.Calculate the percentage uncertainty in the number of lines per metre suggestedby this marking.'

I'm not sure what the uncertainty/smallest unit of measurement of the instrument used is, since that is all the information they've given. I would appreciate some help.

Thanks!
2. (Original post by Haseeb53)
Hi all,

Hope you are doing fine. I was doing the AS Physics 2014 specimen paper and I couldn't do this question.

'A student has a diffraction grating that is marked 3.5 × 10^3 lines per m.Calculate the percentage uncertainty in the number of lines per metre suggestedby this marking.'

I'm not sure what the uncertainty/smallest unit of measurement of the instrument used is, since that is all the information they've given. I would appreciate some help.

Thanks!
Look at the number of decimal places given for the diffraction grating after converting to metres. Then use rounding for the next decimal place to produce a range for the number of lines per metre.
3. (Original post by uberteknik)
Look at the number of decimal places given for the diffraction grating after converting to metres. Then use rounding for the next decimal place to produce a range for the number of lines per metre.
i dont get it its in "lines per m" so how am i supposed to covert to metres.
4. (Original post by Haseeb53)
Hi all,

Hope you are doing fine. I was doing the AS Physics 2014 specimen paper and I couldn't do this question.

'A student has a diffraction grating that is marked 3.5 × 10^3 lines per m.Calculate the percentage uncertainty in the number of lines per metre suggestedby this marking.'

I'm not sure what the uncertainty/smallest unit of measurement of the instrument used is, since that is all the information they've given. I would appreciate some help.

Thanks!
you from manchester init fam ?

and this is how you do it; ( 0.1x10^3/3.5x103 ) * 100
5. (Original post by yhyh)
i dont get it its in "lines per m" so how am i supposed to covert to metres.
you from manchester too init fam ?

and you convert it by dividing it by 1x10^-3

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