10. If yellow light emitted by sodium lamp in Young’s double slit experiment is replaced by a monochromatic blue light of the same intensity :

9. In Young’s experiment, two coherent sources are placed 0.90 mm apart and fringe are observed one metre away. If it produces second dark fringe at a distance of 1 mm from central fringe, the wavelength of monochromatic light used would be ?

8. The Young’s double slit experiment is performed with blue and with green light of wavelengths 4360Å and 5460Å respectively. If x is the distance of 4th maxima from the central one, then :

7. In Young’s double slit experiment, the fringe width is found to be 0.4 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 ?

6. The periodic waves of intensities I1 and I2 pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:

5. Colours appear on a thin soap film and on soap bubbles due to the phenomenon of ?

4. 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 ?

3. Ratio of intensities of two waves are given by 4 : 1. Then the ratio of the amplitudes of the two waves is ?

2. Interference is possible in ?

1. Which one of the following phenomena is not explained by Huygens construction of wavefront?

76. An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of ?

75. A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance :

74. In an astronomical telescope in normal adjustment a straight black line of length L is drawn on inside part of objective lens. The eyepiece forms a real image of this line. The length of this image is l. The magnification of the telescope is :

73. If the focal length of objective lens is increased then magnifying power of :

72. For a normal eye, the cornea of eye provides a converging power of 40D and the least converging power of the eye lens behind the cornea is 20D. Using this information, the distance between the retina and the eye lens of the eye can be estimated to be ?

71. The magnifying power of a telescope is 9 . When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are :

70. A microscope is focussed on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should the microscope be moved to get the mark in focus again ?

69. A telescope has an objective lens of 10 cm diameter and is situated at a distance of one kilometer 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 ?

68. An astronomical telescope has a length of 44 cm and tenfold magnification. The focal length of the objective lens is ?

67. The hypermetropia is a ?