Wave Optics

Which of the following does NOT describe a wavefront?

The phase difference between two points on a ray separated by a distance $\lambda$ is:

The time taken by light to travel between any two wavefronts along any ray is:

Which of the following statements is true for a wavefront?

If the wavelength of light in vacuum is $6000$ \AA, what is its wavelength in a medium of refractive index $1.5$ according to Huygens' principle?

A spherical wavefront of radius $R$ is incident on a plane mirror. The reflected wavefront will be:

When a plane wavefront is incident on a boundary between two media, the reflected and refracted wavefronts are also plane. This is because:

A plane wavefront is incident normally on a transparent slab of thickness $L$ (extending from $z=0$ to $z=L$). The refractive index of the slab varies along the $x$-direction (parallel to the entry face) according to the relation $n(x) = n_0 + \alpha x$, where $\alpha$ is a small positive constant. According to Huygens' principle and the concept of optical path length, which of the following best describes the emergent wavefront as it exits the slab at $z=L$?

A wavefront incident on an interface is partly reflected and partly refracted. According to Huygens' principle, the reflected and refracted wavefronts are formed by:

When a wavefront passes through a small aperture, it spreads out. This spreading is called diffraction and can be explained by Huygens' principle because:

The angular separation of fringes in YDSE is independent of:

In YDSE, the distance from the central maximum to the $n$-th dark fringe is given by:

If one of the two slits in Young's experiment is covered with an opaque paper, then:

For two waves $y_1 = A \sin(\omega t)$ and $y_2 = A \sin(\omega t + \phi)$, the resultant intensity is maximum when $\phi$ is:

In a YDSE, the distance between the slits is $0.2\text{ mm}$ and the distance to the screen is $1.5\text{ m}$. If the $4^{th}$ bright fringe is $1.5\text{ cm}$ from the central fringe, what is the wavelength of light used?

In the Fresnel biprism experiment, the two virtual sources act as:

At a point on the screen, the path difference for the $5^{th}$ bright fringe is $3 \times 10^{-6}\text{ m}$. What is the wavelength of the light used?

A YDSE is performed using light of wavelength $\lambda$. The distance between the slits is $d$. If the screen is moved from $D_1$ to $D_2$, the change in fringe width is $\Delta \beta$. The wavelength $\lambda$ is given by:

In YDSE, let $I_{max}$ be the intensity of the central maximum. At a distance from the central maximum equal to one-third of the fringe width, the intensity will be:

In a YDSE, the distance between the screen and the slits is $1.5\text{ m}$ and the slit separation is $0.05\text{ mm}$. If the fringe width is $1.8\text{ cm}$, find the wavelength of the light.

When the slit width is made equal to the wavelength of light used, the first minimum occurs at:

Which of the following statements about diffraction is true?

In a single slit experiment, the condition for the second minimum is that the path difference between the extreme rays is:

If we use a lens to focus the diffraction pattern in Fraunhofer diffraction, the screen is placed at:

At the Fresnel distance, the spread of the beam due to diffraction is:

A telescope has an objective of focal length $100 \text{ cm}$ and diameter $5 \text{ cm}$. If the wavelength of light is $5000 \text{ \AA}$, its resolving power is:

In single slit diffraction, what is the phase difference between the waves from the two ends of the slit for the second minimum?

In a single slit diffraction pattern, if the slit width is $0.5 \text{ mm}$ and the wavelength is $500 \text{ nm}$, find the distance between the first and second minima on a screen $1 \text{ m}$ away.

The semi-angular width of the central maximum in a single slit diffraction pattern is $\theta$. If the slit width is $a$ and the wavelength is $\lambda$, then:

A single slit of width $a$ is illuminated by violet light of wavelength $400 \text{ nm}$. If the violet light is replaced by red light of wavelength $700 \text{ nm}$, the percentage increase in the width of the central maximum is:

In Huygens' construction, the secondary wavelets spread out in all directions with a speed equal to:

If light wavelength is $6000$ Å in vacuum, what is its wavelength in a medium of refractive index $1.5$?

The angle between the incident wavefront and the reflecting surface is called the:

A wavefront incident on a concave mirror results in a reflected wavefront that is:

Which of the following describes the behavior of a plane wavefront after passing through a rectangular glass slab?

In the Huygens construction for a plane wave refraction, the wavefront in the second medium is found by drawing a tangent to the secondary wavelets. If $v_1 < v_2$, the refracted wavefront will:

The distance between two consecutive wavefronts in a monochromatic light wave is equal to:

If the time taken for a secondary wavelet to propagate from a point on the wavefront to the next position is $\Delta t$, the phase change $\Delta \phi$ is:

A wavefront propagates through a series of parallel layers of different refractive indices. The quantity that remains constant for the wavefront across all layers is:

Which of the following describes the wavefront from a very distant star reaching the Earth?

Two waves with amplitudes in ratio 2:3 interfere. The ratio of maximum to minimum intensity is:

If the wavelength of light increases, the path difference for the first bright fringe (excluding central) will:

Which of the following path differences corresponds to a bright fringe?

In incoherent addition, the phase difference $\phi$ varies so rapidly that the average value of $\cos \phi$ over time is:

In a wave optics experiment, two light sources $S_1$ and $S_2$ produce an interference pattern on a screen. Let $I_{max}$ and $I_{min}$ be the maximum and minimum intensities observed in the fringe pattern. If the sources $S_1$ and $S_2$ were to become incoherent, what would be the resulting uniform intensity $I_{incoherent}$ at any point on the screen?

What is the resultant intensity of two incoherent sources of intensities $10 W/m^2$ and $15 W/m^2$?

Superposition of two waves with a phase difference of $2n\pi$ results in:

Two waves with intensities $I_1$ and $I_2$ are incoherent. The resultant intensity $I$ is $I_1 + I_2$. This happens because the time average of $\cos(\phi_1(t) - \phi_2(t))$ is:

In an interference pattern, energy is:

If two waves have an intensity ratio of $k$, the ratio $(I_{max} + I_{min}) / (I_{max} - I_{min})$ is:

Which material is commonly used to make a Polaroid?

A polaroid is rotated in the path of a light beam. If the intensity of transmitted light remains constant, the incident light is:

For unpolarised light incident on a polariser, the transmitted intensity $I$ is related to incident intensity $I_i$ as:

The ordinary ray in a double refracting crystal obeys:

In Malus' Law $I = I_0 \cos^2 \theta$, $I_0$ represents:

Polarisation can be achieved by scattering of light by air molecules. This is based on the fact that the scattered light in a direction perpendicular to the incident beam is:

The ratio of intensities of the two beams is 1:4. If they are polarised in perpendicular planes and then made to interfere, the resultant intensity is:

A polaroid is placed in front of a source of unpolarized light of intensity $I_0$. Another polaroid is placed in front of the first one such that its axis is at an angle of $30^\circ$ with the first. A third polaroid is placed such that its axis is at $30^\circ$ with the second. The final intensity is:

If the angle of incidence is the polarising angle $\theta_p$, then the angle between the reflected and refracted rays is:

A beam of light is incident on a polarizer. If the polarizer is rotated, the intensity varies from $I_{max}$ to $I_{min}$. The ratio $I_{min}/I_{max} = 0.5$. This indicates the beam is: