The maximum speed in m/s at which the 8th bright fringe will move is .
24.00 to 24.15
y8 = 8 Dd | dy8dt | = 8 Dd2 | d(d)dt |, with d(d)dt = 0.04 10-3 0.08 t = 3.2 10-6 t m/s.
At the mean position ( t = 1, d = 0.8 mm): v = 4.8 10-6 3.2 10-6(0.8 10-3)2 = 2.4 10-5 m/s = 24 m/s.
(Maximising td2 exactly shifts the peak slightly to t -0.1, giving 24.12 m/s; to the intended accuracy v 24 m/s.)
Answer: 24.00
In the List-I, four optical effects are mentioned. The physical phenomena of light which are essential to describe these optical effects are given in List-II. Choose the option which describes the correct match between the entries in List-I to those in List-II.
In a single slit diffraction experiment, a slit of width (0.016 0.002) mm is used to measure the wavelength of a monochromatic light source. In the diffraction pattern, the angular distance between the central maximum and first minimum is measured to be (2 40'). The value of the fractional error in the measurement of wavelength is: [Given: (2 )=0.035]
As shown in the figure, a ray AB of unpolarized light enters from water of refractive index nw=4/3 into a medium of refractive index np=4/ 3 after passing through a glass plate of refractive index ng=1.5 and a layer of water. At a particular incident angle i the reflected ray CD is polarized in the direction as shown in the figure. The value of i (in degrees) is: [figure]
A solid glass sphere of refractive index n= 3 and radius R contains a spherical air cavity of radius R2, as shown in the figure. A very thin glass layer is present at the point O so that the air cavity (refractive index n=1) remains inside the glass sphere. An unpolarized, unidirectional and monochromatic light source S emits a light ray from a point inside the glass sphere towards the periphery of the glass sphere. If the light is reflected from the point O and is fully polarized, then the angle of incidence at the inner surface of the glass sphere is . The value of is [figure]
In a Young's double slit experiment, a combination of two glass wedges A and B, having refractive indices 1.7 and 1.5, respectively, are placed in front of the slits, as shown in the figure. The separation between the slits is d=2 mm and the shortest distance between the slits and the screen is D=2 m. Thickness of the combination of the wedges is t=12 . The value of l as shown in the figure is 1 mm. Neglect any refraction effect at the slanted interface of the wedges. Due to the combination of the wedges, the central maximum shifts (in mm) with respect to O by [figure]
A point source S emits unpolarized light uniformly in all directions. At two points A and B, the ratio r=IA/IB of the intensities of light is 2. If a set of two polaroids having 45 angle between their pass-axes is placed just before point B, then the new value of r will be .
The 8th bright fringe above the point O oscillates with time between two extreme positions. The separation between these two extreme positions, in micrometer ( m), is .