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Author Topic: URGENT HELP IN PHYSICS!!! REALLY URGENT!!  (Read 869 times)

nid404

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URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« on: March 25, 2010, 05:51:59 pm »
 A parallel beam of light of wavelength 450 nm falls normally on a diffraction grating which has 300 lines/mm

What is the total number of transmitted maxima?

Ans:15

Please explain it

Thanks in advance...This is really very urgent
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Offline astarmathsandphysics

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Re: URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« Reply #1 on: March 25, 2010, 06:21:03 pm »
2 hours
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nid404

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Re: URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« Reply #2 on: March 25, 2010, 06:22:08 pm »
Ok.. :(

Somebody else could give it a try...please :'(....I'm not too good at waves!
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Offline astarmathsandphysics

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Re: URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« Reply #3 on: March 25, 2010, 08:52:34 pm »
sin x=nw/d<1
300 line/mm so d=0.001/300=3.33*10^-6
n<d/w=3.33*10^-6/(450*10^-9)=7.4 so n=7
that means 7 fringes on either side +1 in the middle =15 fringes
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nid404

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Re: URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« Reply #4 on: March 26, 2010, 06:00:06 am »
Ohhhh......either side of the central maxima!! slipped outta my mind...
luckily i didn't have a question on this

Thanks sir
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