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Answer the following questions: (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?

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Anonym0us
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(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?

Qalaxia Info Bot
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I found an answer from www.britannica.com

Light - Young's double-slit experiment | Britannica


Light - Light - Young's double-slit experiment: The observation of interference effects ... However, as the slits are narrowed in width, the light diffracts into the ... ( Diffraction is itself caused by the wave nature of light, being another example of an ... waves results in a series of equally spaced bands, or fringes, of high intensity, ...


For more information, see Light - Young's double-slit experiment | Britannica

Qalaxia QA Bot
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I found an answer from physics.stackexchange.com

Fringe width and spacing and number of slits in diffraction experiments


The first thing to note is that each of the slits produces a diffraction pattern the ... a slit in a particular direction is controlled by the diffraction pattern due to a single slit. ... The intensity of the fringes produced by the interference of light from the slits is ... For example the double slit pattern in the middle would appear to have slits ...


For more information, see Fringe width and spacing and number of slits in diffraction experiments

Qalaxia Master Bot
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I found an answer from www.khanacademy.org

Young's double slit introduction (video) | Khan Academy


, the wave diffracts to form circular waves. How do you identify the peaks and the valleys in the circular waves? Reply.


For more information, see Young's double slit introduction (video) | Khan Academy

Qalaxia Knowlege Bot
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I found an answer from en.wikipedia.org

Double-slit experiment - Wikipedia


In the single-slit image, a diffraction pattern (the faint spots on either side of the main band) forms due to the nonzero width of the slit. This diffraction pattern is also ...


For more information, see Double-slit experiment - Wikipedia

Pravalika
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a)


Size of the central diffraction band 2x = \frac{2 \lambda D}{a}

              Where, \lambda - wavelength, a - width of slit and D - distance between the screen and slit

                                      x \propto \frac{1}{a}

              Size of the central diffraction band is inversely proportional to slit width.

  

                if the width of the slit is twice the original width a = 2a

                                     x = \frac{2 \lambda D}{2a}

                                       x = \frac{ \lambda D}{a}

           In a single slit diffraction experiment, if the width of the slit is twice the original width, the size of the central diffraction

          band decreases to half.

              

                Intensity I \propto \frac{1}{A}

                Area of central diffraction band  A = \frac{1}{4}

                Intensity = 4 * \text{ (previous intensity) }         

        Therefore, the intensity of the central diffraction band increases to four times.


b)

The pattern of interference in a double-slit experiment is modulated by diffraction from each slit. The pattern is the outcome of the diffracted wave interference from each slit.


c)

Diffraction and interference occur simultaneously. Light waves are diffracted from the edge of a circular obstacle, which interference constructively at the middle of the shadow. A bright spot is created by this constructive interference.

d)

Bending waves by obstacles by a massive angel is possible when the size of the obstacle is equal to the wavelength of the waves.

students are unable to see each other because the wavelength of the light waves is too short relative to the size of the obstacle.  Thus, the diffraction angel is going to be a very small.


Sound waves bend around objects of equal size to their wavelengths. The wall has a similar size to the wavelength of the sound. The effect is called diffraction. Students can converse to each other because the wavelength of the sound waves is the order of the partition height. It creates diffraction to the sound.


e)

The reason is that, in ordinary optical instruments, the size of the aperture concerned is much greater than the wavelength of the ligth used.