« previous next »
Pages: [1]   Go Down

Author Topic: URGENT HELP IN PHYSICS!!! REALLY URGENT!!  (Read 778 times)

nid404

  • Guest
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
Logged

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: URGENT HELP IN PHYSICS!!! REALLY URGENT!!
« Reply #1 on: March 25, 2010, 06:21:03 pm »
2 hours
Logged

nid404

  • Guest
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!
Logged

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
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
Logged

nid404

  • Guest
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
Logged
Pages: [1]   Go Up
« previous next »