Wave Optics · Question 3

In a Young double slit experiment, the wavelength of incident light is 6000 Å, the separation between slits S1 and S2 is 5 cm and the distance between slits plane and screen is 50 cm, as shown in the figure below. If the resultant intensity at P is equal to the intensity due to individual slits, the path difference between interfering waves is Å. [figure]

1. 4000
2. 3000
3. 2000
4. 1000

In Young's double slit experiment, the fringe width of the interference pattern produced on the screen is 2.4 μm. If the experiment is carried out in another medium having refractive index 1.2, the fringe width will be μm.

1. 1.2
2. 2
3. 2.4
4. 2.88

The maximum intensity in a Young's double slit experiment is I0. Distance between the slits (d) is 5 , where is the wavelength of light used. The intensity of the fringe, exactly opposite to one of the slits on the screen, placed at D=10d is .

1. I04
2. I02
3. I0
4. 3I04

A slit of width a is illuminated by light of wavelength . The linear separation between 1st and 3rd minima in the diffraction pattern produced on a screen placed at a distance D from the slit system is .

1. D a
2. 1.5 D a
3. 2 D a
4. 3 D a

A telescope with objective diameter R is used to observe a distant star emitting light of wavelength 500 nm, at a resolution of 5 10-7 radian. The value of R is cm.

1. 61
2. 122
3. 244
4. 305

An unpolarized light is incident on the plane interface of air-dielectric medium shown in figure. If the incident angle is equal to Brewster angle, identify the expression representing reflected wave. [figure]

1. (Ex i+Ey j) (kx-kz- t)
2. (Ex i+Ez k) (kx+ky- t)
3. (Ex j+Ey k) (ky+kz- t)
4. (Ex i+Ey j+Ez k) (kx+ky-kz- t)

An unpolarized light of certain intensity passes through a combination of two polarizers whose transmission axes are at 30° and 90°, respectively, with respect to the horizontal axis. A third polarizer with its transmission axis at 60° with the horizontal axis is placed between the two existing polarizers. The ratio of the output intensities with and without the third polarizer is .

1. 3/4
2. 4/3
3. 9/4
4. 4/9

In a double slit experiment, when one of the slits is covered by a transparent mica sheet of refractive index 1.56, the central fringe shifts to the position of 7th bright fringe, obtained with both slits uncovered. If the light source wavelength is 450 nm, the thickness of mica sheet is 10-9 m. The value of is .

In single slit diffraction pattern, the wavelength of light used is 628 nm and slit width is 0.2 mm, the angular width of central maximum is 10-2 degrees. The value of is .

In a Young's double slit experiment, the intensity at some point on the screen is found to be 34 times of the maximum of the interference pattern. The path difference between the interfering waves at this point is x where is wavelength of the incident light. The value of x is .