JEE Questions for Physics Wave Optics Quiz 8 - MCQExams.com

In the far field diffraction pattern of a single slit under polychromatic illumination, the first minimum with the wavelength λ1 is found to be coincident with the third maximum at λ2 So
  • 3 λ1 = 0.3 λ2
  • 3 λ1 = λ2
  • λ1 = 3.5 λ2
  • 0.3 λ1 = 3
Light of wavelength λ = 5000Å falls normally on a narrow slit. A screen placed at a distance of 1 m from the slit and perpendicular to the direction of light. The first minima of the diffraction pattern is situated at 5 mm from the centre of central maximum. The width of the slit is
  • 0.1 mm
  • 1.0 mm
  • 0.5 mm
  • 0.2 mm
A single slit Fraunhoffer diffraction pattern is formed with white light. For what wavelength of light the third secondary maximum in the diffraction pattern coincides with the second secondary maximum in the pattern for red light of wavelength 6500 Å?
  • 4400 Å
  • 4100 Å
  • 4642.8 Å
  • 9100 Å
A single slit of width a is illuminated by violet light of wavelength 400 nm and the width of the diffraction pattern is measured as y. When half of the slit width is covered and illuminated by yellow light of wavelength 600 nm, the width of the diffraction pattern is
  • The pattern vanishes and the width is zero
  • y / 3
  • 3y
  • None of the above
The condition for obtaining secondary maxima in the diffraction pattern due to single slit is

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    Physics-Wave Optics-95605.png

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The width of the diffraction band varies
  • Inversely as the wavelength
  • Directly as the width of the slit
  • Directly as the distance between the slit and the screen
  • Inversely as the size of the source from which the slit is illuminated
In the diffraction pattern of a straight slit
  • All bands are uniformly bright
  • All bands are uniformly wide
  • Central band is narrower
  • Central band is wider
The limit of resolution of an optical instrument arises on account of
  • Reflection
  • Diffraction
  • Polarization
  • Interference
Red light of wavelength 625 nm is incident normally on an optical diffraction grating with 2 ×105 lines/m. Including central principal maxima, how many maxima may be observed on a screen which is far from the grating?
  • 15
  • 17
  • 8
  • 16
The angular width of the central maximum of the diffraction pattern in a single slit (of width \'a\') experiment, with λ as the wavelength of light is

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  • 2)
    Physics-Wave Optics-95610.png

  • Physics-Wave Optics-95611.png

  • Physics-Wave Optics-95612.png
A polarizer is used to
  • Reduce intensity of light
  • Produce polarised light
  • Increase intensity of light
  • Produce unpolarized light
Through which character we can distinguish the light waves from sound waves
  • Interference
  • Refraction
  • Polarisation
  • Reflection
The angle of polarisation for any medium is 60°, what will be critical angle for this?

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    Physics-Wave Optics-95614.png

  • Physics-Wave Optics-95615.png

  • Physics-Wave Optics-95616.png
The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refractive index n) is

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  • 2)
    Physics-Wave Optics-95619.png

  • Physics-Wave Optics-95620.png

  • Physics-Wave Optics-95621.png
A polaroid is placed at 45° to an incoming light of intensity I0 . Now the intensity of light passing through polaroid after polarisation would be
  • I0
  • I0 / 2
  • I0 / 4
  • Zero
Plane polarised light is passed through a polaroid. On viewing through the polaroid we find that when the polaroid is given one complete rotation about the direction of the light, one of the following is observed
  • The intensity of light gradually decreases to zero and remains at zero
  • The intensity of light gradually increases to a maximum and remains at maximum
  • There is no change in intensity
  • The intensity of light is twice maximum and twice zero
Heat radiations propagate with the speed of
  • α-rays
  • β-rays
  • Light waves
  • Sound waves
Out of the following statements which is not correct?
  • When unpolarised light passes through a Nicol prism, the emergent light is elliptically polarised
  • Nicol prism works on the principle of double refraction and total internal reflection
  • Nicol prism can be used to produce and analyse polarised light
  • Calcite and Quartz are both doubly refracting crystals
A ray of light is incident on the surface of a glass plate at an angle of incidence equal to Brewster\'s angle ϕ. If µ represents the refractive index of glass with respect to air, then the angle between reflected and refracted rays is
  • 90 + ϕ
  • sin–1(µ cos ϕ)
  • 90°
  • 90° – sin–1 (sin ϕ / µ)
Figure represents a glass plate vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarising angle of 57° with the normal. The electric vector in the reflected light on screen S will vibrate with respect to the plane of incidence in a
Physics-Wave Optics-95624.png
  • Vertical plane
  • Horizontal plane
  • Plane making an angle of 45° with the vertical
  • Plane making an angle of 57° with the horizontal
A beam of light AO is incident on a glass slab (µ = 1.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
Physics-Wave Optics-95626.png
  • The intensity is reduced down to zero and remains zero
  • The intensity reduces down some what and rises again
  • There is no change in intensity
  • The intensity gradually reduces to zero and then again increases
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

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    Physics-Wave Optics-95628.png

  • Physics-Wave Optics-95629.png

  • Physics-Wave Optics-95630.png
A light has amplitude A and angle between analyser and polariser is 60°. Light is reflected by analyser has amplitude

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    Physics-Wave Optics-95633.png

  • Physics-Wave Optics-95634.png

  • Physics-Wave Optics-95635.png
When light is incident on a doubly refracting crystal, two refracted rays-ordinary ray (O–ray) and extra ordinary ray (E–ray) are produced. Then
  • Both O–ray and E–ray are polarised perpendicular to the plane of incidence
  • Both O–ray and E–ray are polarised in the plane of incidence
  • E–ray is polarised perpendicular to the plane of incidence and O–ray in the plane of incidence
  • E–ray is polarised in the plance of incidence and O–ray perpendicular to the plane of incidence
Light passes successively through two polarimeter tubes each of length 0.29 m. The first tube contains dextro rotatory solution of concentration 60 kgm–3 and specific rotation 0.01 rad m2 kg–1. The second tube contains laevo rotatory solution of concentration 30 kg/m3 and specific rotation 0.02 rad m2kg–1. The net rotation produced is
  • 15°
  • 0°
  • 20°
  • 10°
V0 and VE represent the velocities, µ0 and µE the refractive indices of ordinary and extraordinary rays for a doubly refracting crystal. Then
  • V0 ≥ VE , µ0 ≤ µE if the crystal is calcite
  • V0 ≤ VE , µ0 ≤ µE if the crystal is quartz
  • V0 ≤ VE , µ0 ≥ µEif the crystal is calcite
  • V0 ≥ VE , µ0 ≥ µE if the crystal is quartz
Polarising angle for water is 53°4’. If light is incident at this angle on the surface of water and reflected, the angle of refraction is
  • 53°4'
  • 126°56'
  • 36°56'
  • 30°4'
When a plane polarised light is passed through an analyser and analyser is rotated throught 90°, the intensity of the emerging light
  • Varies between maximum and minimum
  • Becomes zero
  • Does not vary
  • Varies between a maximum and zero
Two Nicols are oriented with their principal planes making an angle of 60°. The percentage of incident unpolarized light which passes through the system is
  • 50%
  • 100%
  • 12.5%
  • 37.5%
Unpolarized light falls on two polarizing sheets places one on top of the other. What must be the angle between the characteristic directions of the sheets if the intensity of the first transmitted light is one-third the maximum intensity of the first transmitted beam?
  • 75°
  • 55°
  • 35°
  • 15°
Unpolarized light of intensity 32Wm–2 passes through three polarizers such that transmission axes of the first and second polarizer makes an angle 30° with each other the transmission axis of the last polarizer is crossed with that of the first. The intensity of final emerging light will be
  • 32 Wm–2
  • 3 Wm–2
  • 8 Wm–2
  • 4 Wm–2

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    Physics-Wave Optics-95645.png

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When unpolarised light beam is incident from air onto glass (n = 1.at the polarising angle
  • Reflected beams is polarised 100 percent
  • Reflected and refracted beams are partially polarized
  • The reason for (a) is that almost all the light is reflected
  • All of the above
The Brewster angle for the glass-air interface is 54.74°. If a ray of light going from air to glass strikes at an angle of incidence 45°, then the angle of refraction is
(Hint : tan 54.74° = √2)
  • 25°
  • 60°
  • 30°
  • 54.74°
A beam of natural light falls on a system of 5 polaroids, which are arranged in succession such that the pass axis of each polaroid is turned through 60° with respect to the preceding one. The fraction of the incident light intensity that passes through the system is

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    Physics-Wave Optics-95654.png

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A plane electromagnetic wave travelling along the X-direction has a wavelength of 3 mm. The variation in the electric field occurs in the Y-direction with an amplitude 66 Vm–1. The equations for the electric and magnetic field as a function of x and t respectively

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    Physics-Wave Optics-95659.png

  • Physics-Wave Optics-95660.png

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Pick out the longest wavelength from the following types of radiations
  • Blue light
  • γ-rays
  • X-rays
  • Red light
Wave which cannot travel in vacuum is
  • X-rays
  • Infrasonic
  • Ultraviolet
  • Radiowaves
Which of the following represents an infrared wavelength?
  • 10–4 cm
  • 10–5 cm
  • 10–6 cm
  • 10–7 cm
The speed of electromagnetic wave in vacuum depends upon the source of radiation
  • Increases as we move from y-rays to radio waves
  • Decreases as we move from y-rays to radio waves
  • Is same for all of them
  • None of the above
Which of the following radiations has the least wavelength?
  • γ-rays
  • β-rays
  • α-rays
  • X-rays
The electromagnetic waves travel with a velocity
  • Equal to velocity of sound
  • Equal to velocity of light
  • Less than velocity of light
  • None of the above
The ozone layer absorbs
  • Infrared radiations
  • Ultraviolet radiations
  • X-rays
  • γ-rays
Electromagnetic waves are transverse in nature is evident by
  • Polarization
  • Interference
  • Reflection
  • Diffraction
Which rays are not the portion of electromagnetic spectrum?
  • X-rays
  • Microwaves
  • α-rays
  • Radio waves
Radio waves diffract around building although light waves do not. The reason is that radio waves
  • Travel with speed larger than c
  • Have much larger wavelength than light
  • Carry news
  • Are not electromagnetic waves
Radio waves and visible light in vacuum have
  • Same velocity but different wavelength
  • Continuous emission spectrum
  • Band absorption spectrum
  • Line emission spectrum
Energy stored in electromagnetic oscillations is in the form of
  • Electrical energy
  • Magnetic energy
  • Both (a) and (b)
  • None of these
If a source is transmitting electromagnetic wave of frequency 8.2 × 106 Hz, then wavelength of the electromagnetic waves transmitted from the source will be
  • 36.6 m
  • 40.5 m
  • 42.3 m
  • 50.9 m
In an apparatus, the electric field was found to oscillate with an amplitude of 18 V/m. The magnitude of the oscillating magnetic field will be
  • 4 × 10–6 T
  • 6 × 10–8 T
  • 9 × 10–9 T
  • 11 × 10–11 T
0:0:1


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