Wave Optics

In interference experiment the path difference between two interfering waves at a point A on the screen is /3, where is the wavelength of these waves, and at another point B the path difference is /6. The ratio of intensities at points A and B is .

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

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

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are false
2. Both Statement I and Statement II are true
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

An unpolarised light is incident at an interface of two dielectric media having refractive indices of 2 (incident medium) and 2 3 (refracted medium) respectively. To satisfy the condition that reflected and refracted rays are perpendicular to each other, the angle of incidence is

1. 45
2. 60
3. 10
4. 30

In the Young's double slit experiment the intensity produced by each one of the individual slits is Io. The distance between two slits is 2 mm. The distance of screen from slits is 10 m. The wavelength of light is 6000 . The intensity of light on the screen in front of one of the slits is

1. Io2
2. Io
3. 2Io
4. 4Io

When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is . ( -1(1.52) = 57.7 , refractive indices of air and glass are 1.00 and 1.52, respectively.)

1. 36.3
2. 39.6
3. 42.6
4. 32.3

Which of the following are true for a single slit diffraction?

1. B, D only
2. A, D only
3. A, C, E only
4. B, C only

In a double slit experiment the distance between the slits is 0.1 cm and the screen is placed at 50 cm from the slits plane. When one slit is covered with a transparent sheet having thickness t and refractive index n (= 1.5), the central fringe shifts by 0.2 cm. The value of t is cm.

1. 6.0 10-3
2. 8 10-4
3. 5.0 10-3
4. 5.6 10-4

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :

1. Both Statement I and Statement II are true
2. Statement I is true but Statement II is false
3. Statement I is false but Statement II is true
4. Both Statement I and Statement II are false

In a Young's double slit experiment, the source is white light. One of the slits is covered by red filter and another by a green filter. In this case:

1. there shall be alternate interference fringes of red and green.
2. there shall be an interference pattern for red distinct from that for green.
3. there shall be an interference pattern, where each fringe's pattern center is green and outer edges is red.
4. there shall be no interference fringes.

Two plane polarized light waves combine at a certain point whose electric field components are E1 = E0 t E2 = E0 ( t + 3 ) Find the amplitude of the resultant wave.

1. 1.7 E0
2. E0
3. 0.9 E0
4. 3.4 E0

In a Young's double slit experiment, the slits are separated by 0.2 mm. If the slits separation is increased to 0.4 mm, the percentage change of the fringe width is :

1. 25\%
2. 50\%
3. 0\%
4. 100\%

Two polarisers P1 and P2 are placed in such a way that the intensity of the transmitted light will be zero. A third polariser P3 is inserted in between P1 and P2, at particular angle between P2 and P3. The transmitted intensity of the light passing through all three polarisers is maximum. The angle between the polarisers P2 and P3 is :

1. /6
2. 3
3. 4
4. /8

Two monochromatic light beams have intensities in the ratio 1:9. An interference pattern is obtained by these beams. The ratio of the intensities of maximum to minimum is

1. 8 : 1
2. 4 : 1
3. 3 : 1
4. 9 : 1

Width of one of the two slits in a Young's double slit interference experiment is half of the other slit. The ratio of the maximum to the minimum intensity in the interference pattern is:

1. 3 : 1
2. (2 2 + 1) : (2 2 - 1)
3. 9 : 1
4. (3 + 2 2) : (3 - 2 2)

A light wave is propagating with plane wave fronts of the type x + y + z = constant. The angle made by the direction of wave propagation with the x-axis is :

1. -1(2/3)
2. -1 ( 1 3 )
3. -1 ( 13 )
4. -1 ( 23 )

The Young's double slit interference experiment is performed using light consisting of 480 nm and 600 nm wavelengths to form interference patterns. The least number of the bright fringes of 480 nm light that are required for the first coincidence with the bright fringes formed by 600 nm light is

1. 8
2. 4
3. 5
4. 6

In a Young's double slit experiment, three polarizers are kept as shown in the figure. The transmission axes of P1 and P2 are orthogonal to each other. The polarizer P3 covers both the slits with its transmission axis at 45 to those of P1 and P2. An unpolarized light of wavelength and intensity I0 is incident on P1 and P2. The intensity at a point after P3 where the path difference between the light waves from s1 and s2 is 3, is [figure]

1. I0
2. I03
3. I04
4. I02

Young's double slit interference apparatus is immersed in a liquid of refractive index 1.44. It has slit separation of 1.5 mm. The slits are illuminated by a parallel beam of light whose wavelength in air is 690 nm. The fringe-width on a screen placed behind the plane of slits at a distance of 0.72 m, will be:

1. 0.63 mm
2. 0.33 mm
3. 0.46 mm
4. 0.23 mm

The width of one of the two slits in Young's double slit experiment is d while that of the other slit is x d. If the ratio of the maximum to the minimum intensity in the interference pattern on the screen is 9:4 then what is the value of x ? (Assume that the field strength varies according to the slit width.)

1. 2
2. 3
3. 4
4. 5

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the most appropriate answer from the options given below :

1. (A) is false but (R) is true
2. Both (A) and (R) are true but (R) is not the correct explanation of (A)
3. Both (A) and (R) are true and (R) is the correct explanation of (A)
4. (A) is true but (R) is false

A transparent film of refractive index, 2.0 is coated on a glass slab of refractive index, 1.45. What is the minimum thickness of transparent film to be coated for the maximum transmission of Green light of wavelength 550 nm . [Assume that the light is incident nearly perpendicular to the glass surface.]

1. 68.7 nm
2. 137.5 nm
3. 94.8 nm
4. 275 nm

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason (R). In the light of the above statements, choose the correct answer from the options given below :

1. (A) is true but (R) is false
2. Both (A) and (R) are true and (R) is the correct explanation of (A)
3. (A) is false but (R) is true
4. Both (A) and (R) are true but (R) is NOT the correct explanation of (A)

Light emerges out of a convex lens when a source of light is kept at its focus. The shape of wavefront of the light is :

1. cylindrical
2. spherical
3. plane
4. both spherical and cylindrical