Wave Optics PYQs

In Young’s double slit experiment, using monochromatic light of wavelength λ, the intensity of light at a point on the screen where the path difference is λ is K units. The intensity of light at a point where the path difference is λ/3 will be:

In interference and diffraction, the light energy is redistributed. If it reduces in one region, producing a dark fringe, it increases in another region, producing a bright fringe. A. As there is no gain or loss of energy, these phenomena are consistent with the principle of conservation of energy. B. Diffraction and interference are characteristics exhibited only by light waves. Choose the correct answer from the options given below:

An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster’s angle. Then-

The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5° from the polarization axis of one of the polaroid, is ($I_0$ is the intensity of polarized light after passing through the first polaroid):

If the monochromatic source in Young’s double slit experiment is replaced by white light, then

An unpolarised light beam strikes a glass surface at Brewster’s angle. Then:

For Young’s double slit experiment, two statements are given below: Statement I : If screen is moved away from the plane of slits, angular separation of the fringes remains constant. Statement II : If the monochromatic source is replaced by another monochromatic source of larger wavelength, the angular separation of fringes decreases. In the light of the above statements, choose the correct answer from the options given below:

In a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nm wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is:

The Brewster angle i$_b$ for an interface should be

In Young’s double slit experiment, if the separation between coherent sources is halved and the distance of the screen from the coherent sources is doubled, then the fringe width becomes :

Angular width of the central maxima in the Fraunhofer diffraction for λ = 6000 Å is θ₀. When the same slit is illuminated by another monochromatic light, the angular width decreases by 30%. The wavelength of this light is:

In a Young’s double slit experiment, if there is no initial phase difference between the light from the two slits, a point on the screen corresponding to the fifth minimum has path difference:

In Young's double slit experiment the separation between the slits is 2 mm, the wavelength λ of the light used is 5896 Å and distance D between the screen and slits is 100 cm. It is found that the angular width of fringes is 0.20°. To increase the fringe angular width to 0.21° (with same λ and D) the separation between the slits needs to be changed to:

Unpolarised light is incident from air on a plane surface of a material of refractive index 'μ'. At a particular angle of incidence 'i', it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation?

Two Polaroids $P_1$ and $P_2$ are placed with their transmission axes perpendicular to each other. Unpolarised light of intensity $I_0$ is incident on $P_1$. A third Polaroid $P_3$ is placed between $P_1$ and $P_2$ such that its axis makes an angle $45^\circ$ with that of $P_1$. The intensity of transmitted light through $P_2$ is:

Young's double slit experiment is first performed in air and then repeated in a medium other than air. It is found that the eighth bright fringe in the medium lies where the fifth dark fringe lies in air. The refractive index of the medium is nearly:

The interference pattern is obtained with two coherent light sources of intensity ratio $n$. In the interference pattern, the ratio $$\frac{I_{max}-I_{min}}{I_{max}+I_{min}}$$ will be:

A linear aperture whose width is $0.02\ \text{cm}$ is placed immediately in front of a lens of focal length $60\ \text{cm}$. The aperture is illuminated normally by a parallel beam of wavelength $5 \times 10^{-5}\ \text{cm}$. The distance of the first dark band from the centre of the screen is:

At the first minimum adjacent to the central maximum of a single-slit diffraction pattern, the phase difference between the Huygens wavelet from the edge of the slit and the wavelet from the mid-point of the slit is:

Two slits in Young's experiment have widths in the ratio $1:25$. The ratio of intensity at the maxima and minima in the interference pattern, $\dfrac{I_{\max}}{I_{\min}}$, is:

A beam of light of λ = 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is:

In the Young's double-slit experiment, the intensity of light at a point on the screen where the path difference is λ is K, λ being the wavelength of light used. The intensity at a point where the path difference is λ/4 will be:

In Young's double slit experiment, the slits are $2\,\text{mm}$ apart and are illuminated by photons of wavelengths $\lambda_1=12000\,\text{Å}$ and $\lambda_2=10000\,\text{Å}$. At what minimum distance from the common central bright fringe on a screen $2\,\text{m}$ from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other?