$light diffraction$

The distance between the two slits ( d ) ( Inversely proportional ).

The distance between the observation screen and the double slits screen ( R ) ( directly proportional ).

The wavelength of the used light ( λ ) ( directly proportional ).

Factors affect the distance between two successive fringes of the same kind Light interference is a phenomenon of superposition of light wavesproduced from two coherent sources and produces reinforcement of light in some regions ( bright fringes ) and weakness in other regions ( dark fringes ), Interference fringes is a sequence of bright and dark straight parallel regions.

$light diffraction$

Ĭondition : The path difference of the two interfered waves equals ( m + ½ ) λ, where ( m = 0, 1, 2, …. ĭestructive interference is interference that produces weakness in the intensity of the lightin some regions ( dark fringes ) as a result of meeting a crest of one wave with a trough of another wave.

$light diffraction$

Ĭondition : The path difference of the two interfered waves equals ( mλ ), where ( m = 0, 1, 2, …….or any integer ). Ĭonstructive interference is interference that produces reinforcement in the intensity of the lightin some regions ( bright fringes ) as a result of meaning a crest of one wave with a crest of another wave or a trough of one wave with a trough of another wave. The interference has two types which are constructive interference and destructive interference.

The two light sources must be coherent have the same frequency, amplitude and phase.

Each of the two light sources must be monochromatic.

The distance between two successive fringes of the same kind ( bright or dark ) can be determined from the relation : Δy = λ R / d, where ( λ ) is the wavelength of the used light, ( R ) is the distance between the double slits screen and the observation screen and ( d ) is the distance between the two slits. Wave front is the surface which all its points have the same phase and this surface is perpendicular to the direction of wave propagation, The coherent light sources are the sources that produce waves of the same frequency, amplitude and the same phase. or ( m + ½ ) λ, This is called destructive interference.

$light diffraction$

ĭark regions ( dark fringes ) when a crest from ( S 1 ) meets a trough from ( S 2 ) or a trough from ( S 1 ) meets a crest from ( S 2 ), where the path difference between the two interfered waves is ½ λ, 3 ⁄2λ, 5 ⁄2λ, …….

$light diffraction$

The two waves propagates and when they reach the last screen they give :īright regions ( bright fringes ) when a crest from ( S 1 ) meets a crests from ( S 2 ) or a trough from ( S 1 ) meets a trough from ( S 2 ), where the path difference between the two interfered waves is 0 , λ, 2λ, …….or mλ, This is called constructive interference. On operating the light source, the light waves pass from the slit ( S ) in form of cylindrical waves, The double slits screen at the wave front, So, the produced waves from the double slits have the same phase ( coherent ), The double slits screen acts as a source of two coherent waves. You can get a source of a monochromatic light to explain the light interference phenomenon, So, the wavelength has one constant value, Screen with a rectangular slit ( S ) at an appropriate distance from the light source, Screen with two narrow slits ( S 1 and S 2 )and screen to receive the waves. The light waves interfere when they have the same frequency, amplitude and phase producing regions of constructive interference and regions of destructive interference, They diffract in the same medium when they pass through a slit or by a sharp edge having dimensions near to the wavelength of the light waves. Light waves propagate in straight lines in the homogeneous medium, They reflect when they fall on a reflecting surface, They refract when they travel between two transparent media different in the optical density, according to the laws of refraction.

$light diffraction$

Light diffraction