A parallel beam of electrons travelling in \(x\text-\)direction falls on a slit of width \(d\) (see figure). If after passing the slit, an electron acquires momentum \({p}_{y}\) in the \(y\text-\)direction then for a majority of electrons passing through the slit (\(h\) is Planck's constant):

1. \(|{p}_{y}|{d > h}\)
2. \(|{p}_{y}|{d \gg h}\)
3. \(|{p}_{y}|{d < h}\)
4. \(|{p}_{y}|{d \simeq h}\)
Subtopic:  Diffraction |
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A single slit of width \({b}\) is illuminated by a coherent monochromatic light of wavelength \(\lambda.\) If the second and fourth minima in the diffraction pattern at a distance \(1~\text{m}\) from the slit are at \(3~\text{cm}\) and \(6~\text{cm}\) respectively from the central maximum, what is the width of the central maximum?
(i.e. distance between the first minimum on either side of the central maximum)
1. \(4.5~\text{cm}\)
2. \(6.0~\text{cm}\)
3. \(3.0~\text{cm}\)
4. \(1.5~\text{cm}\)
Subtopic:  Diffraction |
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A single slit of width \(0.1~\text{mm}\) is illuminated by a parallel beam of light of wavelength \(6000~\mathring A\) and diffraction bands are observed on a screen \(0.5~\text{m}\) from the slit. The distance of the third dark band from the central bright band is:
1. \(3~\text{mm}\)
2. \(1.5~\text{mm}\)
3. \(9~\text{mm}\)
4. \(4.5~\text{mm}\)
Subtopic:  Diffraction |
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The angular width of the central maximum in a single slit diffraction pattern is \(60^\circ\). The width of the slit is \(1~\mu\text{m}\). The slit is illuminated by monochromatic plane waves. If another slit of same width is made near it, Young's fringes can be observed on a screen placed at a distance \(50~\text{cm}\) from the slits. If the observed fringe width is \(1~\text{cm}\), what is the slit separation distance? (i.e. distance between the centers of each slit.)
1. \(25~\mu\text{m}\)
2. \(50~\mu\text{m}\)
3. \(75~\mu\text{m}\)
4. \(100~\mu\text{m}\)

Subtopic:  Diffraction |
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A light of wavelength \(550~\text{nm}\) falls normally on a slit of width \(22.0 × 10^{–5}~ \text{cm}.\) The angular position of the second minima from the central maximum (in radians) will be:
1. \(\dfrac{\pi}{4}\)

2. \(\dfrac{\pi}{8}\)

3. \(\dfrac{\pi}{12}\)

4. \(\dfrac{\pi}{6}\)
Subtopic:  Diffraction |
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In a double-slit experiment, when a thin film of thickness \(t\) having a refractive index \(\mu\). is introduced in front of one of the slits, the maximum at the centre of the fringe pattern shifts by one fringe width. The value of \(t\) is:
(\(\lambda\) is the wavelength of the light used):
1. \(\frac{\lambda}{2(\mu-1)}\)
2. \(\frac{\lambda}{(2\mu-1)}\)
3. \(\frac{2\lambda}{(\mu-1)}\)
4. \(\frac{\lambda}{(\mu-1)}\)

Subtopic:  Diffraction |
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Orange light of wavelength \(6000 \times 10^{-10} ~\text{m}\) illuminates a single slit of width \(0.6 \times 10^{-4} ~\text{m}\). The maximum possible number of diffraction minima produced on both sides of the central maximum is:
1. \(200\)
2. \(198\)
3. \(400\)
4. \(126\)

Subtopic:  Diffraction |
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Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter \(0.1 ~\mathrm{\mu m}\). if the diameter of the pinhole is slightly increased, it will affect the diffraction pattern such that:

1. its size decreases, and intensity decreases.
2. its size increases, and intensity increases.
3. its size increases, but intensity decreases.
4. its size decreases, but intensity increases.

Subtopic:  Diffraction |
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In a single-slit diffraction experiment, light of wavelength, \(\lambda=600\) nm is used and the first minimum is observed at an angle, \(\theta=30^\circ.\) The width of the slit \((a)\) is:
1. \(1.2\) \(\mu \text{m}\) 2. \(1.5\) \(\mu \text{m}\)
3. \(1.0\) \(\mu \text{m}\) 4. \(1.8\) \(\mu \text{m}\)
Subtopic:  Diffraction |
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In a single slit diffraction pattern with slit width \(a\) and wavelength of light \(\lambda,\) then the angular position of first minima if screen distance \(D~(D \gg a)\) is:
1. \({\lambda\over a}\)
2. \({2\lambda\over a}\)
3. \({3\lambda\over 2a}\)
4. \({3\lambda\over a}\)
Subtopic:  Diffraction |
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