Question
Diffraction MC in a single -slit diffraction pattern ,(a) all maximum have the same width,(b) the central maximum is twice as wide as the side maximum the side maximum are twice as wide as the central maximum (d) none of the proceeding MC As the number of lines for the unit length of a diffraction grating increases ,the spacing between the maximum (a)increases (b) decreases (c) remains unchanged MC In the single slit diffraction pattern if the wave length of light increase the width of the central maximum will increase (b) decrease (c) remains the same At what angle will the second second order diffraction maximum be seen from a diffraction greating of spacing 1.25 mu m when illuminated by light of wavelength 550nm ? A venetian blind is essentially a diffraction greating not for visible light but for waves with longer wave length if the spacing between the slates of a blind is 2.5cm (a) for what wave length is there a first order maximum at an angle of 10 degree and (b) what type of radiation is this? A diffraction greating is designed to have the second order maximum at 10 degree from the central maximum for the red end (lambda=700nm) of the visible spectram How many lines for the contimeter does the grating have? Find the angles of the blue (lambda=420nm) and red (lambda=680nm) component of the first and second order maxima in a pattern produced by a diffraction greating with 7500 lines/cm IE White light rangeng from blue(40mm) to red (700nm) illuminate a diffraction greating with 8000 lines/cm (a) For the first maxima , the (1) blue (2)red color is closer to central maximum Explain (b) What are the angles of the first order maximum for blue and red ?
Explanation / Answer
38)
We know that
dsintheta =mlamda
and we also know that sintheta =y1/L
Therefore d(y1/L) =mlamda
y1 is directley proportional to lamda
Where y1 is the width of cental maxima , therfore if lamda increases , will also increases.
49)
The separation between the lines is given by (d) =1/7500 =1.33*10-6m
The angle between the first order maxima for the blue light is given by
dsintheta =mlamda
sintheta =m*lamda/d
theta =Sin-1(m*lamda/d) (since m= 1)
=sin-1(400*10-9/1.33*10-6m ) =17.5027degrees
The angle between the first order maxima for the red light is given by
dsintheta =mlamda
sintheta =m*lamda/d
theta =Sin-1(m*lamda/d) (since m= 1)
=sin-1(700*10-9/1.33*10-6m ) =32.5789degrees
The angle between the blue and red light is (theta) =32.5789 -17.5027 =15.0762degrees
44)
We know that
dsintheta =mlamda
Given that
d=1.25*10-6m
wavelength (lamda) =550nm =550*10-9m
m =2 for the second order
dsintheta =mlamda
sintheta =m*lamda/d
theta =sin-1(m*lamda/d) =sin-1(2*550*10-9m/1.25*10-6m) =61.6423degrees
