Single Slit Diffraction

Q. At the first minima, adjacent to the central maxima of a single - slit diffraction pattern, the phase difference between the Huygens wavelet from the edge of the slit and the wavelet from the midpoint of the slit is

1. $\frac{\pi }{8}$ radian
2. $\frac{\pi }{4}$ radian
3. $\frac{\pi }{2}$ radian
4. $\pi$ radian

Q. What is the difference between spatial and temporal coherence and what do we use in the youngs double slit experiment for interference

Q.

Explain the formation of colours in thin films (example soap film).

Q. A beam of light of wavelength $400nm$ from a distant source falls on a single slit $1mm$ wide and the resulting diffraction pattern is observed on a screen $1m$ away. What is the distance between the first dark fringes on either side of central bright fringe?

1. $0.6mm$
2. $0.2mm$
3. $0.8mm$
4. $1.2mm$

Q.

In Young’s double-slit experiment using monochromatic light of wavelengthλ, the intensity of light at a point on the screen where path difference is λ, is K units. What is the intensity of light at a point where path difference is λ /3?

Q. The equation of stationary wave is y=2Asin(2πct/lambda) cos( 2πx/lambda) . Which of the following statements is incorrect

Q.

In Young's double slit experiment, if one of the slit is closed fully, what will be visible on the screen?

1. The bright fringes will become fainter

2. A bright slit will be observed, no interference pattern will exist

3. The bright fringes will become more bright

4. None of the above

Q.

Find the angle of minimum deviation for an equilateral prism made of a material of refractive index 1.732. What is the angle of incidence for this deviation ?

Q.

What will happen if a wedge-shaped film is placed in white light?

Q. A transparent cube of side \(d\), made of a material of refractive index \(\mu_2\), is immersed in a liquid of refractive index \(\mu_1(\mu_1< \mu_2)\). A ray is incident on the face \(AB\), at an angle \(\theta\) (shown in the figure). Total internal reflection takes place at point \(E\) on the face \(BC\). Then \(\theta\) must satisfy,


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Q. The box of a pinhole camera of length $L$, has a hole of radius '$a$'. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$, the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size, say $b_{min}$, when

1. $a=\frac{{\lambda }^2}{L}$ and $b_{min}=\frac{{2\lambda }^2}{L}$
2. $a=\sqrt{\lambda L}$ and $b_{min}=\frac{{2\lambda }^2}{L}$
3. $a=\sqrt{\lambda L}$ and $b_{min}=\sqrt{4\lambda L}$
4. $a=\frac{{\lambda }^2}{L}$ and $b_{min}=\sqrt{4\lambda L}$

Q.

What are coherent sources? How are they realized in practice?

Q.

What will be the angular position for the first minimum due to Fraunhoffer diffraction with sources of light of wave length 550 nm and slit of width 0.55 mm

1. 0.001 rad

2. 0.01 rad

3. 1 rad

4. 0.1 rad

Q.

The penetration of light into the region of geometrical shadow is caused due to______.

1. Refraction

2. Polarisation

3. Interference

4. Diffraction

Q. For a single slit of width 'a', the first minima of the interference pattern of a monochromatic source of light of wavelength lambda occurs at an angle of lambda/a. For the same angle of lambda/a, we get a maxima for two narrow slits separated by 'a'. How can this be explained?

Q. A ray $\text{OP}$ of a monochromatic light is incident on the face $\text{AB}$ of prism $\text{ABCD}$ near vertex $\text{B}$ at an incident angle of ${60}^{\circ }$ as shown in figure. If the refractive index of the material of the prism is $\sqrt{3}$, which of the following is $($are$)$ correct?
[Assume, Prism is surrounded by air medium]

1. The ray gets totally internally reflected at face $\text{CD}$.
2. The ray comes out through face $\text{AD}$.
3. The angle between the incident ray and the emergent ray is ${90}^{\circ }$.
4. The angle between the incident ray and the emergent ray is ${120}^{\circ }$.

Q.

The Young's double slit experiment is performed with blue and with green light of wavelengths 4360 A and 5460 A respectively. If X is the distance of 4th maximum from the central one, then:

1. X(blue) = X(green)

2. X(blue) < X(green)

3. X(blue) > X(green)

4. $\frac{X\left(blue\right)}{X\left(green\right)}=\frac{5460}{4360}$

Q. Two coherent monochromatic sources A and B emit light of wavelength $\lambda$. The distance between A and B is integral multiple of $\lambda$. If a light detector is moved along a line CD, parallel to AB from $-\infty$ to $+\infty$, 8 minimas are observed. Choose the correct options.

1. The distance between AB is $4\lambda$
2. If the detector is moved along X-axis from B to $\infty$, then 5 maximas will be observed
3. At a distance of $x=\frac{15\lambda }{24}$ first minima will be observed
4. At a distance of $x=\frac{15\lambda }{28}$ first minima will be observed

Q. A parallel beam of monochromatic light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At the first minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of the slit is :

1. zero
2. $\frac{\pi }{2}$
3. $\pi$
4. $2\pi$

Q.

LIght of wavelength 560 nm goes through a pinhole of diameter 0.20 mm and falls on a wall at a distance of 2.00 m. What will be th eradius of the central bright spot formed on the wall?

Q. In a YDSE experiment, I_0 is given to be intensity of the central bright fringe and β is the fringe width. Then, at a distance y from the Central Bright Fringe, the intenity will be:-

Q. what is the main cause of chromatic aberration?

1. Dispersion
2. Interference
3. Diffraction
4. Reflection

Q. Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material of the prism is $\mu$, a ray incident at an angle $\theta$, on the face AB would get transmitted through the face AC of the prism, provided

1. $\theta >si{n}^{-1}\left[\mu sin(A-si{n}^{-1}\left(\frac{1}{\mu }\right))\right]$
2. $\theta <si{n}^{-1}\left[\mu sin(A-si{n}^{-1}\left(\frac{1}{\mu }\right))\right]$
3. $\theta >co{s}^{-1}\left[\mu sin(A+si{n}^{-1}\left(\frac{1}{\mu }\right))\right]$
4. $\theta <co{s}^{-1}\left[\mu sin(A+si{n}^{-1}\left(\frac{1}{\mu }\right))\right]$

Q. A parallel beam of light is incident from air at an angle $\alpha$ on the side $\text{PQ}$ of a right angled triangular prism of refractive index $\mu =\sqrt{2}.$ Light undergoes total internal reflection at the face $\text{PR}$ when $\alpha$ has a minimum value of ${45}^{\circ }$. The angle $\theta$ of the prism is:

1. ${15}^{\circ }$
2. ${22.5}^{\circ }$
3. ${30}^{\circ }$
4. ${45}^{\circ }$

Q. 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? Explain ?

Q. A linearly polarized light can be obtained from an unpolarized light by which of the following method(s)?

1. Polarization by Reflection
2. Polarization by Scattering
3. Polarization by Refraction
4. All of the above

Q. The fraunhofer diffraction pattern of a single slit is formed at the focal plane of a lens of focal length $f$. The distance between $1^{st}$ and $2^{nd}$ maxima on screen is $y$ and $a$ is slit width. Then the wave length of light used is

1. $\frac{ay}{3f}$
2. $\frac{3f}{ya}$
3. $\frac{2f}{ay}$
4. $\frac{ay}{f}$

Q. Answer the following questions: (a) In a single slit diffraction experiment, the width of the slit ismade double the original width. How does this affect the sizeand intensity of the central diffraction band? (b) In what way is diffraction from each slit related to theinterference pattern in a double-slit experiment? (c) When a tiny circular obstacle is placed in the path of light froma distant source, a bright spot is seen at the centre of the shadowof the obstacle. Explain why? (d) Two students are separated by a 7 m partition wall in a room10 m high. If both light and sound waves can bend around obstacles, how is it that the students are unable to see eachother even though they can converse easily. (e) Ray optics is based on the assumption that light travels in astraight line. Diffraction effects (observed when light propagatesthrough small apertures/slits or around small obstacles)disprove this assumption. Yet the ray optics assumption is socommonly used in understanding location and several otherproperties of images in optical instruments. What is the justification?

Q.

Do the Lasers produce the Coherent light ?

Q. width of slit in a single slit diffraction experiment such that 20 maxima of double slit interference pattern are obtained within central maxima of the diffraction pattern is ( slit separation for double slit arrangement = 2mm ) (1) 0.05 mm (2) 0.1 mm (3)0.2 mm (4) 0.4 mm