(a) In a single slit diffraction experiment, the width of the slit is made double the original width How - Physics - Wave Optics

Question

(a) In a single slit diffraction experiment, the width of
the slit is made double the original width How does this affect the
size and intensity of the central diffraction band?
(b) In what way is diffraction from each slit related to
the interference pattern in a double-slit experiment?
(c) When a tiny circular obstacle is placed in the path
of light from a distant source, a bright spot is seen at the centre
of the shadow of the obstacle Explain why?
(d) Two students are separated by a 7 m partition wall in
a room 10 m high If both light and sound waves can bend around
obstacles, how is it that the students are unable to see each other
even though they can converse easily
(e) Ray optics is based on the assumption that light
travels in a straight line Diffraction effects (observed when light
propagates through small apertures/slits or around small obstacles)
disprove this assumption Yet the ray optics assumption is so
commonly used in understanding location and several other
properties of images in optical instruments What is the
justification?

Ruhhi Ralhan · Accepted Answer

Dear Student,

The width of central fringe extends upto first secondary minima on both the sides i.e.

$β_{0} = 2 y_{1}$

We know,

$y_{1} = \frac{D λ}{a} o r, β_{0} = \frac{2 D λ}{a}$

So, if we double the slit size the width of the central maxima decreases by half.

When the width of the central maxima is reduced to half, the area of the central diffraction band will become one fourth. Therefore, the intensity becomes four times.