Diffraction Grating Question

1

Hi. anyone knows how to do this? I can't do it. =(

Question:
2. Red light of wavelength 7.00 x 10-7 ("ten to the minus seven") m, incident normally on a diffraction grating, gave first order maximum at an angle of 75°.

(a) Calculate the spacing of the diffraction grating.

(b) Calculate the angle at which the first order maximum for violet light of wavelength 4.50 x 10-7 ("ten to the minus seven") m would be observed.

(c) At what angle or angles would a detector receive radiation which is of wavelength 7.50 x 10-7 ("ten to the minus seven") m transmitted by the grating? Explain your answer.

Reply 1

Itchynscratchy

10

I think this is a braggs law question

λ=2dsinθ

So for a):

d=λ/2sinθ
=7E-07/2 X sin 75
=3.62E-7

b)

θ = arcsin(λ/2d)
=arcsin(4.5E-7/2 X 3.62E-7)
=38°

Not really sure what you mean by c) have yu typed it correctly? :confused:

Reply 2

walalang

OP

1

Itchynscratchy

I think this is a braggs law question

λ=2dsinθ

So for a):

d=λ/2sinθ
=7E-07/2 X sin 75
=3.62E-7

b)

θ = arcsin(λ/2d)
=arcsin(4.5E-7/2 X 3.62E-7)
=38°

Not really sure what you mean by c) have yu typed it correctly? :confused:

Ooopss.. yeah I typed it wrong so I've changed it now... :p:

Thanks so much for the answer... :willy:

Reply 3

walalang

OP

1

Itchynscratchy

I think this is a braggs law question

λ=2dsinθ

So for a):

d=λ/2sinθ
=7E-07/2 X sin 75
=3.62E-7

b)

θ = arcsin(λ/2d)
=arcsin(4.5E-7/2 X 3.62E-7)
=38°

Not really sure what you mean by c) have yu typed it correctly? :confused:

umm.. when I typed 7E-07/2 X sin 75 in my calculator.. I got -1.35E-07 not 3.62E-7. :confused:

I don't get it... :redface:

Diffraction Grating Question

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