Physics Paper 2!!

[libra94]

can somelone please expalin me question 4 (b) and tell me why cant we use x=λD/a this equation to find the distance between the grating [a- in this equation]????
here's the link: http://www.xtremepapers.me/CIE/Internat ... _qp_21.pdf

 

[libra94]

anyone???

 

[msk]

that is used for double slit experiment because in lamda=ax/d we use the seperation of slits as well!

 

[libra94]

that is used for double slit experiment because in lamda=ax/d we use the seperation of slits as well!

in the question they are asking to find the number of lines per metre on the grating
which means that first we have to find the seperation of the grating lines, and then divide the answer by 1 to get the number of lines.

my question is that, why cant we use this, x=λD/a, and then substitute the equation to find a (which is the seperation os the grating) ??
in the marking scheme it says that we should use d sin theta = λn

plz clear me out :!: :!:

 

[msk]

see there is only on slit...what does x stand for in this equation?
x=seperation of slit
so if u have one slit u cant use this formula

 

[libra94]

nooo, x is the fringe seperation not the seperation of the slits :!:

 

[princesszahra]

can somelone please expalin me question 4 (b) and tell me why cant we use x=λD/a this equation to find the distance between the grating [a- in this equation]????
here's the link: http://www.xtremepapers.me/CIE/Internat ... _qp_21.pdf

cuz the width of the grid is not compareable to lambda!!!!!!!!!so easy u ppl!!!!!!!!!!

 

[libra94]

:ugeek:

 

[msk]

can somelone please expalin me question 4 (b) and tell me why cant we use x=λD/a this equation to find the distance between the grating [a- in this equation]????
here's the link: http://www.xtremepapers.me/CIE/Internat ... _qp_21.pdf

cuz the width of the grid is not compareable to lambda!!!!!!!!!so easy u ppl!!!!!!!!!!

could u please explain that...i didn,t get it!

 

[DragonCub]

Maybe you got confused with Young's Double Slit & the Diffraction grating.

lambda = aX / D is used in Young's Double Slit - when there are ONLY TWO apertures. (Here lambda = wavelength, a = distance between the slits, X = fringe gap width, D = the distance from the Young's Double Slit to the screen.)

And for diffraction grating, d*sin() = n * lambda should be used - when there are Thousands (EVEN MILLIONS) of tiny slits (that's way they are called the gratings).

 

[libra94]

oh haan, thnks!!
i knew i was doing some silly mistake here!