Title 10.WAVE OPTICS - Questions.pdf ✅

10.WAVE OPTICS (1.)Maxwell’s equations describe the fundamental laws of (a.) Electricity only (b.) Magnetism only (c.) Mechanics only (d.) Both (a) and (b) (2.)A single slit is located effectively at infinity in front of a lens of focal length 1 m and it is illuminated normally with light of wavelength 600 nm. The first minima on either side of central maximum are separated by 4 mm. Width of the slit is ...... (a.) 0.1 mm (b.) 0.2 mm (c.) 0.3 mm (d.) 0.4 mm (3.)In a Young’s double slit experiment, the fringe width will remain same, if (D = distance between screen and plane of slits, d = separation between two slits and λ = wavelength of light used) (a.) Both λ and D are doubled (b.) Both d and D are doubled (c.) D is doubled but d is halved (d.) λ is doubled but d is halved (4.)The fringe width in Young’s double slit experiment increases when (a.) Wavelength increases (b.) Distance between the slits increases (c.) Distance between the source and screen decreases (d.) The width of the slits increases (5.)Which of following can not be polarized (a.) Radio waves (b.) Ultraviolet rays (c.) Infrared rays (d.) Ultrasonic waves (6.)Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are (a.) 5I and I (b.) 5I and 3I (c.) 9I and I (d.) 9I and 3I (7.)Pick out the longest wavelength from the following types of radiations (a.) Blue light (b.) γ-rays (c.) X-rays (d.) Red light (8.)In a Young’s double slit experiment, the slit separation is 1mm and the screen is 1m from the slit. For a monochromatic light of wavelength 500 nm, the distance of 3rd minima from the central maxima is (a.) 0.50 mm (b.) 1.25 mm (c.) 1.50 mm (d.) 1.75 mm (9.)Wave which cannot travel in vacuum is (a.) X-rays (b.) Infrasonic (c.) Ultraviolet (d.) Radiowaves (10.)The electromagnetic waves do not transport (a.) Energy (b.) Charge (c.) Momentum (d.) Information (11.)An electromagnetic wave, going through vacuum is described by E = E0 sin(kx − ωt). Which of the following is independent of wavelength (a.) k (b.) ω (c.) k/ω (d.) kω (12.)A radio receiver antenna that is 2 m long is oriented along the direction of the electromagnetic wave and receives a signal of intensity 5 × 10−16W/m2 . The maximum instantaneous potential difference across the two ends of the antenna is (a.) 1.23 μV (b.) 1.23 mV (c.) 1.23 V (d.) 12.3 mV (13.)If we observe the single slit Frunhofer diffraction with wavelength λ and slit width e, the width of the central maxima is 2θ. On decreasing the slit width for the same λ (a.) θ increases (b.) θ remains unchanged (c.) θ decreases (d.) θ increases or decreases depending on the intensity of light (14.)A point source of electromagnetic radiation has an average power output of 800 W. The maximum
value of electric field at a distance 4.0 m from the source is (a.) 64.7 V/m (b.) 57.8 V/m (c.) 56.72 V/m (d.) 54.77 V/m (15.)A plane wavefront (λ = 6 × 10−7m) falls on a slit 0.4 mm wide. A convex lens of focal length 0.8m placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum (a.) 6mm (b.) 12mm (c.) 3mm (d.) 9mm (16.)Which one of the following have minimum wavelength (a.) Ultraviolet rays (b.) Cosmic rays (c.) X-rays (d.) γ-rays (17.)In a Young’s experiment, two coherent sources are placed 0.90 mm apart and the finges are observed one metre away. If it produces the second dark fringe at a distance of 1 mm from the central fringe, the wavelength of monochromatic light used would be (a.) 60 × 10−4 cm (b.) 10 × 10−4 cm (c.) 10 × 10−5 cm (d.) 6 × 10−5 cm (18.)A light wave is incident normally over a slit of width 24 × 10−5 cm. The angular position of second dark fringe from the central maxima is 30°. What is the wavelength of light (a.) 6000 Å (b.) 5000 Å (c.) 3000 Å (d.) 1500 Å (19.)A plane electromagnetic wave of wave intensity 6 W/m2 strikes a small mirror area 40 cm2 , held perpendicular to the approaching wave. The momentum transferred by the wave to the mirror each second will be (a.) 6.4 × 10−7kg − m/s 2 (b.) 4.8 × 10−8kg − m/s 2 (c.) 3.2 × 10−9kg − m/s 2 (d.) 1.6 × 10−10kg − m/s 2 (20.)Oil floating on water looks coloured due to interference of light. What should be the order of magnitude of thickness of oil layer in order that this effect may be observed? (a.) 10,000 Å (b.) 1 cm (c.) 10 Å (d.) 100 Å (21.)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 (a.) 1.2 cm (b.) 1.2 mm (c.) 2.4 cm (d.) 2.4 mm (22.)Which if the following phenomena is not common to sound and light waves? (a.) Interference (b.) Diffraction (c.) Coherence (d.) Polarisation (23.)How fast a person should drive his car so that the red signal of light appears green? (Wavelength for red colour = 6200Å and wavelength for green colour = 5400Å) (a.) 1.5 × 108m/s (b.) 7 × 107m/s (c.) 3.9 × 107m/s (d.) 2 × 108m/s (24.)In Fresnel’s biprism experiment is held in water instead of air, then what will be the effect on fringe width (a.) Decreases (b.) Increases (c.) No effect (d.) None of these (25.)In Young’s double slit interference experiment, the slit separation is made 3 fold. The fringe width becomes (a.) 1/3 times (b.) 1/9 times (c.) 3 times (d.) 9 times (26.)In a Young’s double slit experiment using red and blue lights of wavelengths 600 nm and 480 nm respectively, the value of n from which the n th red fringe coincides with (n + 1) the blue fringe is (a.) 5 (b.) 4 (c.) 3 (d.) 2 (27.)In Fresnel’s biprism (μ = 1.5) experiment the distance between source and biprism is 0.3 m and that between biprism and screen is 0.7m and angle of prism is 1°. The fringe width with light of wavelength 6000 Å will be (a.) 3 cm
(b.) 0.011 cm (c.) 2 cm (d.) 4 cm (28.)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 incident beam. At the first maximum of the diffraction pattern, the phase difference between the rays coming from the edges of the slit is (a.) 0 (b.) π 2 (c.) π (d.) 2π (29.)A rocket is moving away from the earth at a speed of 6 × 107m/s. The rocket has blue light in it. What will be the wavelength of light recorded by an observer on the earth (wavelength of blue light = 4600 Å) (a.) 4600 Å (b.) 5520 Å (c.) 3680 Å (d.) 3920 Å (30.)Light of wavelength λ = 5000 Å falls normally on a narrow slit. A screen placed at a distance of 1m 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 (a.) 0.1 mm (b.) 1.0 mm (c.) 0.5 mm (d.) 0.2 mm (31.)A thin mica sheet of thickness 2 × 10−6m 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 (a.) 2 fringes upward (b.) 2 fringes downward (c.) 10 fringes upward (d.) None of these (32.)The distance between the first dark and bright band formed in Young’s double slit experiment with band width B is (a.) B 4 (b.) B (c.) B 2 (d.) 3B 2 (33.)A plane wave of wavelength 6250 Å is incident normally on a slit of width 2 × 10−2 cm. The width of the principal maximum on a screen distant 50 cm will be (a.) 312.5 × 10−3 cm (b.) 312.5 × 10−4 cm (c.) 312 cm (d.) 312.5 × 10−5 cm (34.)Maximum diffraction takes place in a given slit for (a.) γ − rays (b.) Ultraviolet light (c.) Infrared light (d.) Radiowaves (35.)In Fresnel’s biprism experiment, on increasing the prism angle, fringe width will (a.) Increase (b.) Decrease (c.) Remain unchanged (d.) Depend on the position of object (36.)A slit 5 cm wide is irradiated normally with microwaves of wavelength 1.0 cm. Then the angular spread of the central maximum on either side if incident light is nearly (a.) 1/5 rad (b.) 4 rad (c.) 5 rad (d.) 6 rad (37.)Which of the following phenomena can explain quantum nature of light (a.) Photoelectric effect (b.) Interference (c.) Diffraction (d.) Polarization (38.)In the set up shown in figure, the two slits S1and S2 are not equidistant from the slit S. The central fringe at O is, then (a.) Always bright (b.) Always dark (c.) Either dark or bright depending on the position of S (d.) Neither dark nor bright (39.)The 21 cm radio wave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction is atomic hydrogen. the energy of the emitted wave is nearly (a.) 10−17Joule (b.) 1 Joule (c.) 7 × 10−8 Joule (d.) 10−24Joule
(40.)Irreducible phase difference in any wave of 5000 Å from a source of light is (a.) π (b.) 12π (c.) 12π × 106 (d.) π × 106 (41.)In an electromagnetic wave, the amplitude of electric field is 1 V/m, the frequency of wave is 5 × 1014Hz. The wave is propagating along z-axis. The average energy density of electric field, in Joule/ m3 , will be (a.) 1.1 × 10−11 (b.) 2.2 × 10−12 (c.) 3.3 × 10−13 (d.) 4.4 × 10−14 (42.)In Young’s double slit experiment a minima is observed when path difference between the interfering beam is (a.) λ (b.) 1.5λ (c.) 2λ (d.) 2.25λ (43.)The limit of resolution of an optical instrument arises on account of (a.) Reflection (b.) Diffraction (c.) Polarization (d.) Interference (44.)Fringes are obtained with the help of a biprism in the focal plane of an eyepiece distance 1 m from the slit. A convex lens produces images of the slit in two positions between biprism and eyepiece. The distances between two images of the slit in two positions are4.05 × 10−3m and 2.90 × 10−3m respectively. The distance between the slits will be (a.) 3.43 × 10−3m (b.) 0.343m (c.) 0.0343m (d.) 43.3m (45.)When one of the slits of Young’s experiment is covered with a transparent sheet of thickness 4.8 mm, the central fringe shifts to a position originally occupied by the 30th bright fringe. What should be the thickness of the sheet if the central fringe has to shift to the position occupied by 20th bright fringe (a.) 3.8 mm (b.) 1.6 mm (c.) 7.6 mm (d.) 3.2 mm (46.)The phenomenon of diffraction of light was discovered by (a.) Huyghen (b.) Newton (c.) Fresnel (d.) Grimaldi (47.)Light of wavelength 6000 Å falls on a single slit of width 0.1 mm. The second minimum will be formed for the angle of diffraction of (a.) 0.08 rad (b.) 0.06 rad (c.) 0.12 rad (d.) 0.012 rad (48.)Light waves travel in vacuum along the y – axis. Which of the following may represent the wavefront? (a.) y = constant (b.) x = constant (c.) z = constant (d.) x + y + z = constant (49.)In Young’s double alit experiment, the seventh maximum with wavelength λ1 is at a distance d1 and the same maximum with wavelength λ2 is at distanced2. Then d1/d2 = (a.) λ1 λ2 (b.) λ2 λ1 (c.) λ1 2 λ2 2 (d.) λ2 2 λ1 2 (50.)Red light is generally used to observe diffraction pattern from single slit. If blue light is used instead of red light, then diffraction pattern (a.) Will be more clear (b.) Will contract (c.) Will expanded (d.) Will not be visualized (51.)The phenomenon of interference is shown by (a.) Longitudinal mechanical waves only (b.) Transverse mechanical waves only (c.) Electromagnetic waves only (d.) All the above types of waves (52.)Plane microwaves are incident on a long slit having a width of 5 cm. The wavelength of the microwaves if the first minimum is formed at 30° is (a.) 2.5 cm (b.) 2 cm (c.) 25 cm (d.) 2 mm (53.)The maximum distance upto which TV transmission from a TV tower of height h can be received is proportional to (a.) h 1/2 (b.) h (c.) h (d.) h 2