List of top Physics Questions on Wave optics asked in Indian Institute Of Technology Joint Admission Test for MSc

The ultraviolet catastrophe in the classical (Rayleigh-Jeans) theory of cavity radiation is attributed to the assumption that

Linearly polarized light (free space wavelength 𝜆₀= 600nm) is incident normally on a retarding plate (𝑛_𝑒-𝑛_𝑜 = 0.05 at 𝜆₀= 600nm). The emergent light is observed to be linearly polarized, irrespective of the angle between the direction of polarization and the optic axis of the plate. The minimum thickness (in µm) of the plate is:

Suppose that there is a dispersive medium whose refractive index depends on the wavelength as given by \(n(λ) = n_0 +\frac{ a}{λ^2}-\frac{b}{λ^4}\) . The value of 𝜆 at which the group and phase velocities would be the same, is:

Consider two different Compton scattering experiments, in which X-rays and γ rays of wavelength (λ) 1.024Å and 0.049Å, respectively, are scattered from stationary free electrons. The scattered wavelength (λ′) is measured as a function of the scattering angle (θ). If Compton shift is 𝛥λ=λ′−λ, then which of the following statement(s) is/are true:
( h = 6.63 x10^-34J.s, m_e = 9.11x10^-31 kg, c = 3 x 10⁸m/s )

A collimated light beam of intensity 𝐼₀ is incident normally on an air-dielectric (refractive index 2.0) interface. The intensity of the reflected light is _______𝐼₀. (Rounded off to two decimal places)

For a simple cubic crystal, the smallest inter-planar spacing d that can be determined from its second order of diffraction using monochromatic X-rays of wavelength 1.32Å is _________Å. (Round off to two decimal places)

Consider a thick biconvex lens (thickness t=4cm and refractive index n=1.5) whose magnitudes of the radii of curvature R1 and R2, of the first and second surfaces are 30cm and 20cm, respectively. Surface 2 is silvered to act as a mirror. A point object is placed at point A on the axis (OA= 60cm) as shown in the figure. If its image is formed at point Q, the distance d between O and Q is_____ cm. (Rounded off to two decimal places)

A rotating disc is held in front of a plane mirror in two different orientations which are (i) angular momentum parallel to the mirror and (ii) angular momentum perpendicular to the mirror. Which of the following schematic figures correctly describes the angular momentum (solid arrow) and its mirror image (shown by dashed arrows) in the two orientations ?

A linearly polarized light of wavelength 590 nm is incident normally on the surface of a 20 μm thick quartz film. The plane of polarization makes an angle 30° with the optic axis. Refractive indices of ordinary and extraordinary waves differ by 0.0091, resulting in a phase difference of fπ between them after transmission. The value of f (rounded off to two decimal places) and the state of polarization of the transmitted light is

The phase velocity v_p of transverse waves on a one-dimensional crystal of atomic separation d is related to the wavevector k as
\(v_p=C\frac{\sin(kd/2)}{(kd/2)}\)
The group velocity of these waves is

An oil film in air of thickness 255 nm is illuminated by white light at normal incidence. As a consequence of interference, which colour will be predominantly visible in the reflected light ?
Given the refractive index of oil = 1.47

In a X-Ray tube operating at 20 kV, the ratio of the de-Broglie wavelength of the incident electrons to the shortest wavelength of the generated X-rays is ________ (rounded off to two decimal places).
Given: e/m ratio for an electron = 1.76×10¹¹ Ckg-1 and the speed of light in vacuum is 3×10⁸ ms ^-1

A point source emitting photons of 2 eV energy and 1 W of power is kept at a distance of 1m from a small piece of a photoelectric material of area 10^-4 m² . If the efficiency of generation of photoelectrons is 10%, then the number of photoelectrons generated are 𝑓×10¹² per second. The value of 𝑓 is __________ (rounded off to two decimal places).
Given: 1eV = 1.6 × 10⁻¹⁹ J

The spectral energy density u_T(λ) vs wavelength (λ) curve of a black body shows a peak at λ = λ_max. If the temperature of the black body is doubled, then

A wave travelling along the x-axis with y representing its displacement is described by (𝑣 is the speed of the wave)

An objective lens with half angular aperture 𝛼 is illuminated with light of wavelength 𝜆. The refractive index of the medium between the sample and the objective is 𝑛. The lateral resolving power of the optical system can be increased by

In the Compton scattering of electrons, by photons incident with wavelength λ,

A linearly polarized light beam travels from origin to point A (1,0,0). At the point A, the light is reflected by a mirror towards point B (1, -1,0). A second mirror located at point B then reflects the light towards point C (1,-1,1). Let n(x, y, z) represent the direction of polarization of light at (x, y, z).

Which one of the following figures correctly depicts the intensity distribution for Fraunhofer diffraction due to a single slit? Here, x denotes the distance from the centre of the central fringe and I denotes the intensity.

A normal human eye can distinguish two objects separated by 0.35 m when viewed from a distance of 1.0 km. The angular resolution of eye is _________ seconds (Round off to the nearest integer).

The dispersion relation for certain type of waves is given by \(\omega=\sqrt{k^2+a^2}\), where k is the wave vector and a is a constant. Which one of the following sketches represents v_g, the group velocity?