(i.e. distance between the centres of each slit.)
π/3, 2π/3 and π. When they are superposed, the intensity of the resulting wave is nI0. The
value of n is
On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam :
A beam of unpolarised light of intensity I0 is passed through a polaroid A and then through another polaroid B which is oriented so that its principal plane makes an angle of 45° relative to that of A. The intensity of the emergent light is:
In the Young’s double slit experiment using a monochromatic light of wavelength λ, the path difference (in terms of an integer n) corresponding to any point having half the peak intensity is
Two coherent point sources S1 and S2 are separated by a small distance ‘d’ as shown. The fringes obtained on the screen will be:
Using the expression 2d sin θ = λ, one calculates the values of d by measuring the corresponding angles θ in the range 0 to 90°. The wavelength λ is exactly known and the error in θ is constant for all values of θ. As θ increases from 0°,
In Young’s double slit experiment, the slits are 2mm apart and are illuminated by photons of two wavelengths. At what minimum distance from the common central bright fringe on the screen 2m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other?
Young’s double slit experiment is carried out by using green, red and blue light, one color at a time. The fringe widths recorded are and, respectively. Then,
Reason The central fringe is bright or dark that is independent upon the initial phase difference between the two coherence sources.
Reason For interference of two waves the phase difference between the waves must remain constant.
Reason 10−7 m is the order of wavelength of visible light.
Reason Objective lens of large diameter collects more light.
Reason For interference pattern to observe, path difference between two waves is of the order of few wavelengths.
Column I shows four situations of standard Young’s double slit arrangement with the screen placed far away from the slits and In each of these cases and where is the wavlength of the light used. In the cases and a transparent sheet of refractive index and thickness is pasted on slit The thicknesses of the sheets are different in different cases. The phase difference between the light waves reaching a point on the screen from the two slits is denoted by and the intensity by Match each situation given in Column I with the statement(s) in Column II valid for the sitaution
|Column I||Column II|
(A) 4 mm
(B) 5.6 mm
(C) 14 mm
(D) 28 mm
(a) What is the shape of the interference fringes on the screen?
(b) Calculate the ratio of the minimum to the maximum intensities in the interference fringes formed near the point P (shown in the figure).
(c) If the intensity at point P corresponds to a maximum, calculate the minimum distance through which the reflecting surface AB should be moved, so that the intensity at P is again maximum.
below P and 2 m from the vessel, to illuminate the slits as shown in the figure. Calculate the position of the central bright fringe on the other wall CD with respect to the line OQ. Now, a liquid is poured into the vessel and filled up to OQ. The central bright fringe is found to be at Q. Calculate the refractive index of the liquid.