Chapter Wave Optics Q1. Which one of the following phenomena is not explained by Huygen s construction of wave front? [1988] (a) Refraction Reflection Diffraction Origin of spectra Q2. Which of the following phenomenon is not common to sound and light waves? [1988] (a) Interference Diffraction Coherence Polarisation Q3. Interference is possible in [1989] (a) light waves only sound waves only both light and sound waves neither light nor sound waves Q4. The Young s double slit experiment is performed with blue and with green light of wavelengths 4360Åand 5460Årespectively. If x is the distance of 4th maxima from the central one, then [1990] (a) x (blue) = x (green) x (blue) > x (green) x (blue) < x (green) x(blue)/x(green)=5460/3260 Q5. In Young s double slit experiment, the fringe width is found to be0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3, without disturbing the geometrical arrangement, the new fringe width will be [1990] (a) 0.30 mm 0.40 mm 0.53 mm 450 microns Q6. In Young s experiment, two coherent sources are placed0.90 mm apart and fringe are observed one meter away. If it produces second dark fringe at a distance of 1 mm from central fringe, the wavelength of monochromatic light used would be [1991, 1992] (a) 60 10 4 cm 10 10 4 cm 10 10 5 cm 6 10 5 cm Q7. Ratio of intensities of two waves are given by 4: 1. Then the ratio of the amplitudes of the two waves is (a) 2: 1 1: 2 4: 1 1: 4 Q8. In Young s double slit experiment carried out with light of wavelength (O) = 5000Å, the distance between the slits is0.2 mm and the screen is at 200 cm from the slits. The central maximum is at x = 0. The third maximum (taking the central maximum as zeroth maximum) will be at x equal to (a) 1.67 cm 1.5 cm 0.5 cm 5.0 cm Q9. If yellow light emitted by sodium lamp in Young s double slit experiment is replaced by a monochromatic blue light of the same intensity (a) fringe width will decrease [1992] finge width will increase fringe width will remain unchanged fringes will become less intense Q10. Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observer will see [1993] (a) no interference interference with brighter bands interference with dark bands interference fringe with larger width Q11. A parallel beam of monochromatic light of wavelength 5000Åis incident normally on a single narrow slit of width0.001 mm. The light is focused by a convex lens on a screen placed in focal plane. The first minimum will be formed for the angle of diffraction equal to [1993] (a) 0 15 30 50 Q12. In a Fresnel biprism experiment, the two positions of lens give separation between the slits as 16 cm and 9 cm respectively. What is the actual distance of separation? [1996] (a) 12.5 cm
12 cm 13 cm 14 cm Q13. Colours appear on a thin soap film and on soap bubbles due to the phenomenon of [1999] (a) refraction dispersion interference diffraction Q14. Which of the following shows particle nature of light? [2001] (a) refraction interference polarization photoelectric effect Q15. Apaper, with two marks having separation d, is held normal to the line of sight of an observer at a distance of 50m. The diameter of the eye-lens of the observer is 2 mm. Which of the following is the least value of d, so that the marks can be seen as separate? The mean wavelength of visible light may be taken as 5000 Å. [2002] (a) 1.25 m 12.5 cm 1.25 cm 2.5 mm Q16. The periodic waves of intensities I 1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is: [2008] Q18. In Young s double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths λ 1 = 12000Åand λ 2 = 10000Å. At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other? [NEET 2 013] (a) 6 mm 4 mm 3 mm 8 mm Q19. A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct? [NEET 2 013] (a) The angular width of the central maximum of the diffraction pattern will increase. The angular width of the central maximum will decrease. The angular width of the central maximum will be unaffected. Diffraction pattern is not observed on the screen in case of electrons. (a) Q17. Alens having focal length f and aperture of diameter forms an image of intensity I. Aperture of diameter d/2 in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively: [2010] (a) Q20. In Young s double slit experiment the distance between the slits and the screen is doubled. The separation between the slits is reduced to half. As a result the fringe width [NEETKar. 2013] (a) is doubled is halved becomes four times remains unchanged Q21. A parallel beam of light of wavelength O 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 second minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is [NEETKar. 2013]
(a) Q1. Q11. Q2. Q12. Q3. Q13. Q4. Q5. Q14. Q6. Q15. Q7. Q8. Q9. Q16. Q10.
Q17. Q18. Q19.
Q20. Q21.