Optics

The angle of deviation for a prism is the angle between:

Which of the following factors does not affect the focal length of a lens?

The value of refractive index of vacuum is:

If a lens has a focal length of $-20\text{ cm}$, what type of lens is it?

A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is $4/3$ and the fish is $12\text{ cm}$ below the surface, the radius of the circle is:

A thin lens has a focal length of $10\text{ cm}$. When the object is placed at $15\text{ cm}$ from the lens, the image is formed at $30\text{ cm}$. If the object is moved to $30\text{ cm}$, where is the image formed?

A ray of light is incident at the critical angle on the interface between a medium and air. If the refractive index of the medium is $2$, the angle of refraction in air is:

A small object is placed $10\text{ cm}$ in front of a plane glass slab of thickness $6\text{ cm}$ ($n=1.5$). The distance of the image from the front surface of the slab is:

A ray of light passes through a glass sphere of radius $R$ and refractive index $n$ such that it passes through the center of the sphere. The total deviation suffered by the ray is:

An object is placed $12\text{ cm}$ in front of a lens to form an image on a screen. When the lens is shifted by $4\text{ cm}$, another image is formed on the same screen. The focal length of the lens is:

In a combination of two lenses in contact, if the focal lengths are $f_1$ and $f_2$, the equivalent focal length $F$ is given by:

If $f_v$ and $f_r$ are the focal lengths of a convex lens for violet and red light respectively, then:

The image formed by a concave lens for a real object is always:

A ray of light passing through the principal focus of a convex lens, after refraction, will emerge:

A lens has a power of $+5D$. If it is kept in contact with another lens such that the combination has a focal length of $-20\text{ cm}$, the power of the second lens is:

A point object is placed at $30\text{ cm}$ from a convex lens of focal length $20\text{ cm}$. The distance of the image from the lens is:

If a biconvex lens is submerged in a liquid with refractive index $\mu_l$ such that $\mu_l < \mu_g$ (refractive index of glass), its focal length will:

A convex lens of focal length $f$ produces a real image $m$ times the size of the object. The distance of the object from the lens is:

For a thin lens with radii $R_1$ and $R_2$, if $R_1 = R_2 = R$ and it is a biconcave lens of refractive index $n$, the focal length $f$ is:

A lens is made of glass ($n=1.5$) and has focal length $20\text{ cm}$ in air. It is immersed in a liquid of refractive index $n=1.5$. Its focal length will be:

A simple microscope is basically a:

The objective lens of a telescope forms an image of a distant object. This image serves as the __________ for the eyepiece.

Which of the following is used to view objects on the surface of the Earth?

The tube length of an astronomical telescope in normal adjustment is 105 cm. If the magnifying power is 20, the focal length of the objective is:

A student is adjusting a compound microscope to view a specimen such that the final image is formed at the least distance of distinct vision ($D = 25\text{ cm}$). The flowchart below shows the progression of image formation through the optical system. For this specific adjustment, what is the nature of the intermediate image $I_1$ and its required position relative to the eyepiece lens of focal length $f_e$?

The magnifying power of a simple microscope is 5 when the image is at the near point. What is its focal length?

If a telescope has a magnifying power of 5 and the distance between the objective and eyepiece is $36\text{ cm}$ in normal adjustment, what are the focal lengths of the lenses?

An astronomical telescope is set for normal adjustment (final image at infinity). The objective lens has a focal length $f_o$ and a diameter $D$, while the eyepiece has a focal length $f_e$. The eyepiece forms a real image of the objective lens, which is often called the 'eye-ring' or exit pupil. If the diameter of this exit pupil is $d$, which of the following expressions correctly represents the magnifying power $M$ of the telescope?

The primary reason for using a large aperture objective in an astronomical telescope is to:

A telescope uses an objective mirror with a radius of curvature of $2.4\text{ m}$ and an eyepiece of focal length $1.2\text{ cm}$. The magnifying power of this reflecting telescope is:

In the construction of wavefronts, the primary wavefront is considered to be the:

The concept of secondary wavelets was introduced by:

As a spherical wavefront propagates outwards from a point source, the energy per unit area (intensity):

A point source of light is at the focus of a converging lens. The rays emergent from the lens are parallel. The emergent wavefront is:

In the Huygens' construction for refraction at a plane interface between medium 1 (refractive index $n_1$) and medium 2 (refractive index $n_2$), a plane wavefront $AB$ is incident such that $A$ is on the interface and $B$ is in medium 1. If the disturbance from $B$ takes time $t$ to reach point $C$ on the interface (covering a distance $BC$), and the secondary wavelet from $A$ travels a distance $r$ in medium 2 during the same time interval $t$, which of the following expressions correctly relates $r$ and $BC$?

A plane wavefront is incident on a boundary between two media. If the wavefronts in the second medium are further apart than in the first, it implies:

Which factor in the Huygens-Fresnel theory explains why light does not travel in the backward direction?

The 'Envelope' in Huygens' construction is defined as the surface that is:

In the derivation of reflection using Huygens' principle, we consider a triangle $ABC$ and a reflected triangle $ADC$. The equality of these triangles proves $i = r$. This proof relies on the fact that the secondary wavelets from different points on the wavefront:

For a cylindrical wavefront, the amplitude $A$ at distance $r$ from the line source is proportional to $r^n$. What is the value of $n$?

Two coherent sources of intensity ratio $100:1$ interfere. What is the ratio of $I_{max}$ to $I_{min}$?

The interference fringes in YDSE are called 'fringes of equal':

If the wavelength of light is $\lambda$, the path difference for the $1^{st}$ dark fringe is:

Which of the following changes would increase the spacing between fringes in YDSE?

If the slit width of one slit is reduced such that its intensity becomes $1/4$ of the other, what happens to the dark fringes?

What is the intensity at a point on the screen where the two waves have a phase difference of $90^\circ$ and each has individual intensity $I$?

In YDSE, how does the fringe width change if the source light is changed from violet to red?

In a YDSE setup, the light source is not monochromatic but consists of two wavelengths $\lambda_1 = 500$ nm and $\lambda_2 = 700$ nm. At what minimum distance from the central maximum will the bright fringe of one coincide with the bright fringe of the other? (Take $D = 1$ m, $d = 1$ mm)

If the separation between the slits is $1$ mm and the screen is $1$ m away, what is the wavelength of light if the fringe width is $0.5$ mm?

In YDSE, the intensity at a point $P$ on the screen is $I$. If the path difference at $P$ is $\lambda/6$, the ratio of $I$ to the maximum intensity $I_{max}$ is:

The intensity of the first secondary maximum in a single slit diffraction pattern is roughly:

Sound waves can be diffracted more easily than light waves because sound waves have:

Which of the following cannot be used to polarize light?

In a single slit diffraction experiment, the phase difference between the waves from the two edges of the slit for the first minimum is:

If the slit width in a single slit diffraction experiment is made equal to the wavelength of the light used, what is the angular width of the central maximum?

The resolving power of an optical instrument is:

Two polaroids are placed with their transmission axes at right angles. A third polaroid is placed between them such that its axis bisects the angle between the first two. What fraction of the incident unpolarized light intensity $I_0$ emerges from the system?

When unpolarized light of intensity $I_0$ passes through two polarizers whose axes are at $60^{\circ}$, the intensity of the light transmitted is:

The secondary maxima in a single-slit diffraction pattern occur at angular positions given by $(a \sin \theta)$ equal to:

For a given wavelength, the resolving power of a microscope with an oil immersion objective ($\mu = 1.5$) compared to an air objective is: