Sarahisme Posted October 10, 2005 Share Posted October 10, 2005 hey i have a question about this question .... ok so for interference maxima the equation is [math] dsin \theta_m = m \lambda [/math] , where m = 0,1,2,... now for the first grating (4000 lines/cm) and the red wavelength: [math] \theta = sin^{-1}(\frac{m \lambda}{d}) [/math] now my question is can i let m be anything i like or whats the deal? because wouldn't there be multiple (theoretically infinite amount) angles that construct interference could happen at? -Sarah Link to comment Share on other sites More sharing options...
swansont Posted October 10, 2005 Share Posted October 10, 2005 hey i have a question about this question .... ok so for interference maxima the equation is [math] dsin \theta_m = m \lambda [/math] ' date=' where m = 0,1,2,... now for the first grating (4000 lines/cm) and the red wavelength: [math'] \theta = sin^{-1}(\frac{m \lambda}{d}) [/math] now my question is can i let m be anything i like or whats the deal? because wouldn't there be multiple (theoretically infinite amount) angles that construct interference could happen at? -Sarah Yes, m can be anything as long as [math] \theta < 90[/math] However, the intensity drops off for higher dffraction angles, so in practice you can't always see them. Link to comment Share on other sites More sharing options...
Sarahisme Posted October 10, 2005 Author Share Posted October 10, 2005 so i assume the correct answer to this question would not really involve plugging in numbers then? or do you just do it for m=1 or something? well the thing is in my textbook, there is a similar question, which just does it for m = 1, but isnt that not enitirely correcct, because it could be done for m =2, m=3,...etc. ??? the reason i ask is because well, since you are given numerical values then shouldn't i be producing a numerical answer? Link to comment Share on other sites More sharing options...
swansont Posted October 10, 2005 Share Posted October 10, 2005 so i assume the correct answer to this question would not really involve plugging in numbers then? or do you just do it for m=1 or something? well the thing is in my textbook' date=' there is a similar question, which just does it for m = 1, but isnt that not enitirely correcct, because it could be done for m =2, m=3,...etc. ??? the reason i ask is because well, since you are given numerical values then shouldn't i be producing a numerical answer?[/quote'] Often you just need to find the first-order maximum or minimum. Depends on the question. Link to comment Share on other sites More sharing options...
Sarahisme Posted October 10, 2005 Author Share Posted October 10, 2005 ok yeah, so in terms of this question do you think it wants an algebraic or a numerical answer? or both? because i think its a bit unclear Link to comment Share on other sites More sharing options...
swansont Posted October 11, 2005 Share Posted October 11, 2005 Since they gave you actual numbers, I think they want a numerical answer. The algebraic answer will be included in the work you do, anyway. Link to comment Share on other sites More sharing options...
Sarahisme Posted October 11, 2005 Author Share Posted October 11, 2005 hmm yeah ok, i'll probably just give the first-order maxima then, because as you say, experimentally thats usually the most useful (easy to find) one. Thanks for all you help swansont! Link to comment Share on other sites More sharing options...
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