YDSE

There are 2 imp approaches in it:

1) Identification of standard YDSE diagram and applying x=yd/D   d<<<D d=Slit seperation, D=distance b/w slits and screen

2) Points of maxima x=n l, minima = (2n-1) l   , so if slit width is a multiple of wavelength=I

After identifying   the approaches u are ready with the solving part so here it goes

*~* Phase diff=2pi/l*Path Difference (applicable only for coherent sources)

*~*If slit width becomes large interference fringes disappear

*~*INTENSITY

-:-Intensity observed I=I1+I2+2(I1*I2) ^0.5cos# where I1, I2 are the intensities transmitted from 1^st and 2^nd slit, #=phase diff b/w interfering light waves

-:-Intensity at maxima= ((I1) ^0.5+ (I2)0.5) ^2 //// Intensity at minima= ((I1) ^0.5-(I2)0.5) ^2

-:-Intensity Ix Amplitude square A^2 (simple 3 markers can be asked with closely resembling options)

-:-Intensity at distance y from central maxima I=4Iocos^2(pi y/d) if I1=I2=Io

-:-If 1 slit is closed the intensity becomes Io, where maximum intensity is 4Io

*~*PATH DIFFERENCES

-:-Always take care of optical path differences apart from geometrical as follows

-:-If light travels a distance d in air/vacuum optical path =geometrical path=d, but in a medium of refractive index u optical path=u d   ; geometrical path= d

-:-If light is reflected it faces a phase lag of pi or path diff of l/2

*~*FRINGE WIDTH

-:-W=D l/d will become Dl/u d if YDSE is performed in any medium E g: water….

-:-Even if transparent sheets are introduced it remains same, the central maxima and hence the entire fringe pattern shifts by the same amt (can be calc easily by taking care of optical path differences)

-:-Angular fringe width o=l/d  o is in radians, so make app conversions if o is given in degrees =>1 degree=pi/180 radians (I seems very easy but q paper me degree se aane wala ans bhi hoga :P….so chances of overconfidence/silly/careless errors)

*~*PLACING OF THE SCREEN

HOPE IT HELPS U TOO!

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