(a) “If the slits in Young’s double slit experiment are identical, then intensity at any point on the screen may vary between zero and four times to the intensity due to single slit”. Justify the above statement through a relevant mathematical expression.
(b) Draw the intensity distribution as function of phase angle when diffraction of light takes place through coherently illuminated single slit.
ANS. 11
(a)
The total intensity at a point where the phase difference is ∅, is
given by 𝐼 = 𝐼ଵ + 𝐼ଶ + 2ඥ𝐼ଵ𝐼ଶ 𝐶𝑂𝑆 ∅. Here 𝐼ଵ and 𝐼ଶ are the intensities of two individual sources which are equal.
When ∅ is 0, I = 4𝐼ଵ.
When ∅ is 90o
, I = 0
Thus intensity on the screen varies between 4𝐼ଵ and 0.
ANS. 11
(b)
Intensity distribution as function of phase angle, when diffraction of
light takes place through coherently illuminated single slit
