A parallel beam of moving electrons is incident normal on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the slit is further narrowed, then which of the following statements is correct?
1. | The diffraction pattern is not observed on the screen in the case of electrons. |
2. | The angular width of the central maximum of the diffraction pattern will increase. |
3. | The angular width of the central maximum will decrease. |
4. | The angular width of the central maximum will remain the same. |
A diffraction pattern is observed using a beam of red light. What will happen if the red light is replaced by the blue light?
1. | No change takes place. |
2. | Diffraction bands become narrower. |
3. | Diffraction bands become broader. |
4. | Diffraction pattern disappears. |
If the wavelength of light used is halved and the numerical aperture of the compound microscope is doubled, then its resolving power will
1. Remain unchanged
2. Doubled
3. Halved
4. Quadrupled
An astronaut is looking down on earth's surface from a space shuttle at an altitude of
. Assuming that the astronaut's pupil diameter is 5 mm and the wavelength of
visible light is 500 nm. The astronaut will be able to resolve linear object of the size of
about
1. 0.5 m
2. 5 m
3. 50 m
4. 500 m
The average distance between the earth and moon is km. The minimum
separation between the two points on the surface of the moon that can be resolved by a telescope whose objective lens has a diameter of 5 m with is
1. 5.65 m
2. 28.25 m
3. 11.30 m
4. 56.51 m
The distance of the moon from earth is . The eye is most sensitive to light of
wavelength 5500 Å. The minimum separation between two points on the moon that can
be resolved by a 500 cm telescope will be
1. 51 m
2. 60 m
3. 70 m
4. All the above
We wish to see inside an atom. Assuming the atom to have a diameter of 100 pm, this
means that one must be able to resolve a width of say 10 p.m. If an electron
microscope is used, the minimum electron energy required is about
1. 1.5 KeV
2. 15 KeV
3. 150 KeV
4. 1.5 KeV
A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometre from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Å, is of the order of
1. 0.5 m
2. 5 m
3. 5 mm
4. 5 cm
The ratio of resolving powers of an optical microscope for two wavelengths is
(1) 8:27
(2) 9:4
(3) 3:2
(4) 16:81
In a diffraction pattern due to a single slit of width a,the first minimum is observed at an angle when light of wavelength 5000 is incident on the slit. The first secondary maximum is observed at an angle of
(a) (b)
(c) (d)
At the first minimum adjacent to the central maximum of a single slit diffraction pattern, the phase difference between the Huygen's wavelet from the edge of the slit and the wavelet from the midpoint of the slit is
(1) π/4 radian
(2) π/2 radian
(3) π radian
(4) π/8 radian
A thin mica sheet of thickness 2×10–6 m and refractive index (μ = 1.5) is introduced in the path of the first wave. The wavelength of the wave used is 5000 Å. The central bright maximum will shift
(1) 2 fringes upward
(2) 2 fringes downward
(3) 10 fringes upward
(4) None of these
In Young's double slit experiment, the distance between the two slits is 0.1 mm and the wavelength of light used is 4×10–7 m. If the width of the fringe on the screen is 4 mm, the distance between screen and slit is
(1) 0.1 mm
(2) 1 cm
(3) 0.1 cm
(4) 1 m
In Young’s experiment, the distance between slits is 0.28 mm and distance between slits and screen is 1.4 m. Distance between central bright fringe and third bright fringe is 0.9 cm. What is the wavelength of used light
(1) 5000 Å
(2) 6000 Å
(3) 7000 Å
(4) 9000 Å
If a transparent medium of refractive index μ = 1.5 and thickness t = 2.5 × 10–5 m is inserted in front of one of the slits of Young’s Double Slit experiment, how much will be the shift in the interference pattern? The distance between the slits is 0.5 mm and that between slits and screen is 100 cm
1. 5 cm
2. 2.5 cm
3. 0.25 cm
4. 0.1 cm
In Young’s experiment, monochromatic light is used to illuminate the two slits A and B. Interference fringes are observed on a screen placed in front of the slits. Now if a thin glass plate is placed normally in the path of the beam coming from the slit
(1) The fringes will disappear
(2) The fringe width will increase
(3) The fringe width will decrease
(4) There will be no change in the fringe width but the pattern shifts
In Young’s double-slit experiment the wavelength of light was changed from 7000 Å to 3500 Å. While doubling the separation between the slits which of the following is not true for this experiment:
(1) The width of the fringes changes
(2) The colour of bright fringes changes
(3) The separation between successive bright fringes changes
(4) The separation between successive dark fringes remains unchanged
In Young’s double-slit experiment, an interference pattern is obtained on a screen by a light of wavelength 6000 Å, coming from the coherent sources S1 and S2. At certain point P on the screen third dark fringe is formed. Then the path difference S1P – S2P in microns is
(1) 0.75
(2) 1.5
(3) 3.0
(4) 4.5
In Young’s double-slit experiment the fringe width is β. If entire arrangement is placed in a liquid of refractive index n, the fringe width becomes
(1)
(2) nβ
(3)
(4)
In Young’s double slit experiment, distance between two sources is 0.1 mm. The distance of screen from the sources is 20 cm. Wavelength of light used is 5460 Å. Then angular position of the first dark fringe is
1. 0.08°
2. 0.16°
3. 0.20°
4. 0.32°
In a Young’s double slit experiment, the slit separation is 0.2 cm, the distance between the screen and slit is 1m. Wavelength of the light used is 5000 Å. The distance between two consecutive dark fringes (in mm) is
(1) 0.25
(2) 0.26
(3) 0.27
(4) 0.28
A slit of width a is illuminated by white light. For red light (λ = 6500 Å), the first minima is obtained at θ = 30°. Then the value of a will be
(1) 3250 Å
(2) 6.5 × 10–4 mm
(3) 1.24 microns
(4) 2.6 × 10–4 cm
What will be the angular width of central maxima in Fraunhoffer diffraction when light of wavelength is used and slit width is 12×10–5 cm
(1) 2 rad
(2) 3 rad
(3) 1 rad
(4) 8 rad
A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is
(1) 1.2 mm
(2) 1.2 cm
(3) 2.4 cm
(4) 2.4 mm
The direction of the first secondary maximum in the Fraunhofer diffraction pattern at a single slit is given by:
(a is the width of the slit)
1.
2.
3.
4.
A parallel monochromatic beam of 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 edges of the slit is:
1. \(0\)
2. \(\pi\over 2
\)
3. \(\pi\)
4. \(2\pi\)
A parallel beam of monochromatic light of wavelength 5000 Å is incident normally on a single narrow slit of width 0.001 mm. The light is focused by a convex lens on a screen placed on the focal plane. The first minimum will be formed for the angle of diffraction equal to:
1. 0o
2. 15o
3. 30o
4. 60o
In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum with the wavelength is found to be coincident with the third maximum at . So
(1)
(2)
(3)
(4)
A beam of light AO is incident on a glass slab (μ = 1.54) in a direction as shown in figure. The reflected ray OB is passed through a Nicol prism on viewing through a Nicole prism, we find on rotating the prism that,
1. the intensity is reduced down to zero and remains zero.
2. the intensity reduces down some what and rises again.
3. there is no change in intensity.
4. the intensity gradually reduces to zero and then again increases.
In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is:
(1) 0o
(2) 45o
(3) 90o
(4) 180o
An unpolarised light incident on a polariser has amplitude A, and the angle between analyzer and polariser is \(60^{\circ}\). The light transmitted by the analyzer has an amplitude of:
1.
2.
3.
4. A/2
Unpolarized light falls on two polarizing sheets placed one on top of the other. What must be the angle between the characteristic directions of the sheets if the intensity of the final transmitted light is one-third the maximum intensity of the first transmitted beam?
(1) 75°
(2) 55°
(3) 35°
(4) 15°
Unpolarized light of intensity 32Wm–2 passes through three polarizers such that transmission axes of the first and second polarizer makes and angle 30° with each other and the transmission axis of the last polarizer is crossed with that of the first. The intensity of final emerging light will be
(1) 32 Wm–2
(2) 3 Wm–2
(3) 8 Wm–2
(4) 4 Wm–2
When an unpolarized light of intensity I0 is incident on a polarizing sheet, the intensity of the light which does not get transmitted is
(1) Zero
(2) I0
(3)
(3)
When the angle of incidence on a material is 60°, the reflected light is completely polarized. The velocity of the refracted ray inside the material is (in ms–1)
1. 3 × 108
2.
3.
4. 0.5 × 108
Two polaroids are placed in the path of unpolarized beam of intensity I0 such that no light is emitted from the second polaroid. If a third polaroid whose polarization axis makes an angle θ with the polarization axis of first polaroid, is placed between these polaroids then the intensity of light emerging from the last polaroid will be:
(1)
(2)
(3)
(4)
In the Young's double slit experiment, if the phase difference between the two waves interfering at a point is ϕ, the intensity at that point can be expressed by the expression-
(where A and B depend upon the amplitudes of the two waves)
(1)
(2)
(3)
(4)
In the figure is shown Young’s double-slit experiment, \(Q\) is the position of the first bright fringe on the right side of \(O.\) \(P\) is the \(11\)th bright fringe on the other side, as measured from \(Q.\) If the wavelength of the light used is \(6000 \times10^{-10}\) m, then \(S_1B\) will be equal to:
1. \(6\times10^{-6}\) m
2. \(6.6\times10^{-6}\) m
3. \(3.1\times10^{-6}\) m
4. \(3.1\times10^{-7}\) m
In Young’s double-slit experiment, the two slits act as coherent sources of equal amplitude A and wavelength λ. In another experiment with the same set up, the two slits are of equal amplitude A and wavelength λ but are incoherent. The ratio of the intensity of light at the mid-point of the screen in the first case to that in the second case is:
(1) 1 : 2
(2) 2 : 1
(3) 4 : 1
(4) 1 : 1
A monochromatic beam of light falls on the YDSE apparatus at some angle (say θ) as shown in the figure. A thin sheet of glass is inserted in front of the lower slit S2. The central bright fringe (path difference = 0) will be obtained:
(1) At O
(2) Above O
(3) Below O
(4) Anywhere depending on angle θ, the thickness of plate t and refractive index of glass μ
Two ideal slits S1 and S2 are at a distance d apart and illuminated by the light of wavelength λ passing through an ideal source slit S placed on the line through S2 as shown. The distance between the planes of slits and the source slit is D. A screen is held at a distance D from the plane of the slits. The minimum value of d for which there is darkness at O is:
(1)
(2)
(3)
(4)
In a single slit diffraction of light of wavelength λ by a slit of width e, the size of the central maximum on a screen at a distance b is
(1)
(2)
(3)
(4)
In a YDSE bi-chromatic light of wavelengths, 400 nm and 560 nm are used. The distance between the slits is 0.1 mm and the distance between the plane of the slits and the screen is 1 m. The minimum distance between two successive regions of complete darkness is:
(1) 4 mm
(2) 5.6 mm
(3) 14 mm
(4) 28 mm
In Young's double-slit experiment, the intensity at a point is (1/4) of the maximum intensity. The angular position of this point is:
(1) sin-1(λ/d)
(2) sin-1(λ/2d)
(3) sin-1(λ/3d)
(4) sin-1(λ/4d)
A beam of electron is used in a YDSE experiment. The slit width is \(d\). When the velocity of the electron is increased, then,
1. | No interference is observed |
2. | Fringe width increases |
3. | Fringe width decreases |
4. | Fringe width remains the same |