QJEEM20Ph9187: JEE Main 2020 Physics - Class 12 JEEM20Ph9187 Solution: In a double slit experiment, at a certain point on the screen…

Question

Verified Solution • 2025–26 Session moderate

In a double slit experiment, at a certain point on the screen the path difference between the two interfering waves is

{1 \over 8}

th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is :

Accepted Answer

\Delta

X =

{\lambda \over 8}

\Delta

\phi

=

{{2\pi } \over \lambda }

\Delta

X =

{{2\pi } \over \lambda }{\lambda \over 8}

=

{\pi \over 4}

I = I₀

{\cos ^2}\left( {{{\Delta \phi } \over 2}} \right)

\Rightarrow

{I \over {{I_0}}}

=

{\cos ^2}\left( {{{{\pi \over 4}} \over 2}} \right)

\Rightarrow

{I \over {{I_0}}}

=

{\cos ^2}\left( {{\pi \over 8}} \right)

= 0.853

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