How would the intereference pattern differ if one of the slits in Young's double slit experiment was covered?

Question

Imagine Young's double slit experiment:

Light waves screen
>>>>>>> l l
>>>>>>> slit1 l
>>>>>>> l l
>>>>>>> l l
>>>>>>> slit 2 l
>>>>>>> l l
l l


How would the interference pattern differ if this experiemtn was carrie dout in water?

Answer 1

In double slit diffraction, the maximas (bright fringe) are given by:

sinθ =nλ/a

where

n is an integer that labels the order of each maximum,
λ is the wavelength,
a is the distance between the slits
θ is the angle at which constructive interference occurs

The minimas (dark fringe) is given by:

sinθ =(n+½)λ/a

If we covered up one of the slit, then the setup becomes a "single-slit" diffraction. There still be will bright and dark fringes, but the intensity (brightness) of the fringe would decrease exponentially as you move away from the center of the brightest fringe. The minimas of a single-slit diffraction is given by:

sinθ =nλ/w

where

w is the width of the slit
n is an integer that labels the order of each minima,
λ is the wavelength,
θ is the angle at which destructive interference occurs


If this experiement were carried out under water, then the difference would be that the distances between the fringes (both bright and dark) wold be reduced slightly due to the fact that light travels slower in water, thus reducing the effective wavelength, i.e.

λ = c/f

λ' = v/f

where v is the velocity of light in water
f is the freqiency of the light
λ' is the effective wavelength of the light in water

Answer 2

Cover one slit and there will be no interference pattern. There would be a bright area fading off left and right.

Light velocity in water is slower than in air (or a vacuum), so if the frequency (color) of the light is the same, the wavelength is shorter; this means the distance between bright and dark bands in the interference pattern will be reduced.

EDIT: in response; if a double-slit is showing diffraction fringes, that means the slits are narrow. If the slits are narrower than the wavelength of light, then a single slit will not show diffraction fringes. A single wide slit will show a weak fringe pattern.

See http://en.wikipedia.org/wiki/Diffraction

Answer 3

the only slit bypass factors spatial coherence to the incident airplane wave which it particularly is theory to return from an prolonged monochromatic source. If the preliminary airplane wave replaced into spatially coherent, then you certainly does now no longer elect the 1st slit. you ought to use a laser no concern. If the laser spot length is adequately extensive for the double slit, which probably is, then you certainly will see the same result and no elect for the 1st single slit bypass might desire to be needed. i even have complete this try interior the bypass with the two an prolonged source and a laser; employing a laser is a lot greater beneficial difficulty-unfastened.