 Home
 Discuss
 Home Work Help
 can u plaese give explanation for wav...
 Entrance Exam
 Home Work Help

0
questions
0
answers
can u plaese give explanation for wave lenght , path difference, path lenght and constructive on distructive inteference??????
Young's Double Slit Experiment
Let A and B be two fine slits, a small distance 'd' apart. Let them be illuminated by a monochromatic light of wavelength l.
MN in the screen is at a distance D from the slits AB. The waves from A and B superimpose upon each other and an interference pattern is obtained on the screen. The point C is equidistant from A and B and therefore the path difference between the waves will be zero and so the point C is of maximum intensity. It is called the central maximum.
For another point P at a distance 'x' from C, the path difference at P = BP  AP.
Now AB = EF = d, AE = BF = D
\D BPF
[Pythagoras theorem]
Similarly in D APE
(on expanding Binomially)
For bright fringes (constructive wavelength) the path difference is integral multiple of wavelength i.e., path difference is nl.
(x therefore represents distance of n^{t}^{h} bright fringe from C)
Now
and so on.
Therefore separation between the centers of two consecutive bright fringe is the width of a dark fringe.
Similarly for dark fringes,
The separation between the centers of two consecutive dark interference fringes is the width of a bright fringe.
The separation between the centers of two consecutive dark interference fringes is the width of a bright fringe.
All bright and dark fringes are of equal width as b_{1} = b_{2}.