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In Fraunhoffer diffraction, the waveleng...

In Fraunhoffer diffraction, the wavelength of light incident on the slit `(d)/(2)` where d is the width of the slit. What will be the number of bright fringes fromed on an infinitely extended screen placed at any distance from the slit ?

Text Solution

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In Fraunhoffer diffraction condition for maximum is,
`dsintheta=(2n+1)(lamda)/(2)" "` where, n=1, 2, 3, ……
but `lamda=(d)/(2)` is given.
`:.dsintheta=(2n+1)(d)/(4)`
`:.sintheta=((2n+1)/(4))`
but `sinthetale1`
`:.(2n+1)/(4)le1`
`:.2n+1le4`
`:.2nle3`
`nle(3)/(2)`
Thus, for integer value of n, its possible value =1, we have two first order maxima for n=1 and central maximum for n=0, so we have total three maxima.
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