Ray optics practice · Mixed difficulty

Magnifying power of an astronomical telescope in near point adjustment is $110 \%$ of its magnifying power in normal adjustment. Then find the focal length of objective when the length of the telescope in normal adjustment is $10 \mathrm{~cm}$. (Take least distance of clear vision $=25 \mathrm{~cm}$ )

Refractive index of material of prism is $\mu=\sqrt{2}$ and the angle of prism is $60^{\circ}$. The angle of incidence for minimum deviation is

A man standing in a swimming pool looks at a stone lying at the bottom. The depth of the swimming pool is $h$. At what distance from the surface of water is the image of the stone formed (Line of vision is normal; Refractive index of water is $n$)

Assertion : Clouds are white.

Reason : Scattering of all colours are same.

A monochromatic beam of light passes from a denser medium into a rarer medium. As a result

Small vales of numerical aperture (NA) decrease the pulse dispersion but increase losses due to

In the visible region, the dispersive powers and the mean angular deviation for crown, and flint glass prisms are $\omega$ and $\omega^{\prime}$ and $d$ and $d^{\prime}$ respectively. When the two prism are combined, the condition of zero dispersion by the combination is

STATEMENT-1:The formula connecting $u, v$ and $f$ for a spherical mirror is valid for mirrors whose sizes are very small compared to their radii of curvature.

STATEMENT-2:Laws of reflection are strictly valid for plane surfaces, but not for large spherical surfaces.

Let the $x - z$ plane be the boundary between two transparent media. Medium $\mathrm{1}$ in $z\,\, \ge \,\,0$ has a refractive index of $\sqrt 2$ and medium $\mathrm{2}$ with $z\,\, < \,\,0$ has a refractive index of $\sqrt 3$. A ray of light in medium $\mathrm{1}$ given by the vector $\mathbf{A} = 6\,\sqrt 3 \hat i + \,\,8\sqrt 3 \hat j\,\,-\,\,10\,\hat k$ is incident on the plane of separation. The angle of refraction in medium $\mathrm{2}$ is

A ray passing through or directed towards centre of curvature of a spherical mirror is reflected such that it trace back of its path, because

A short straight object of height 100 cm lies before the central axis of a spherical mirror, whose focal length has absolute value $f = 40\,cm$. The image of object produced by the mirror is of height 25 cm and has the same orientation of the object. One may conclude from the information.

For an object placed at a distance $2.4 \mathrm{~m}$ from a lens, a sharp focused image is observed on a screen placed at a distance $12 \mathrm{~cm}$ form the lens. A glass plate of refractive index $1.5$ and thickness 1 $\mathrm{cm}$ is introduced between lens and screen such that the glass plate plane faces parallel to the screen. By what distance should the object be shifted so that a sharp focused image is observed again on the screen?

A convex lens $A$ of focal length $\mathrm{20}\,\,\mathrm{cm}$ and a concave lens $B$ of focal length $\mathrm{56}\,\,\mathrm{cm}$ are kept along the same axis with the distance d between them. If a parallel beam of light falling on $A$ leaves $B$ as a parallel beam, then distances $d$ in cm will be

Assertion: The illuminance of an image produced by a convex lens is greater in the middle and less towards the edges.

Reason: The middle part of image is formed by undeflected rays while outer part by inclined rays.

The refractive index of glass is $\mathrm{1}\mathrm{.520}$ for red light and $\mathrm{1}\mathrm{.525}$ for blue light. Let ${D_1}$ and ${D_2}$ be angles of minimum deviation for red and blue light respectively in a prism of this glass. Then ,

The focal length $\left( f \right)$ of a spherical (concave or convex) mirror of radius of curvature $R$ is

Two transparent media A and B are separated by a plane boundary. The speed of light in those media are $1.5 \times {10^8}$ m/s and $2.0 \times {10^8}$ m/s, respectively. The critical angle for a ray of light for these two media is:

Assertion: Radius of curvature of a convex mirror is $20 \mathrm{~cm}$. If a real object is placed at 10 $\mathrm{cm}$ from pole of the mirror, image is formed at infinity.

Reason: When object is placed at focus, its image is formed at infinity.

Two lenses, one concave and the other convex of same power are placed such that their principal axes coincide. If the separation between the lenses is $x$, then

Beams of red, green and violet light are falling on the refracting face of a prism, all at the same angle of incidence, if their angles of deviation are ${\theta _1},\,\,{\theta _2}$ and ${\theta _3}$ respectively, then

The condition of minimum deviation is achieved in an equilateral prism kept on the prism table of a spectrometer. If the angle of incidence is $53^\circ$, the angle of deviation is

The instrument used by doctors for endoscopy works on the principle of

Which of the prism is used to see infrared spectrum of light

You are given four sources of light each one providing a light of a single colour, blue, green and yellow. Suppose the angle of refraction for a beam of yellow light corresponding to a particular angle of incidence at the interface of two media is $90^{\circ}$. Which of the following statement is correct if the source of yellow light is replaced with that of other lights without changing the angle of incidence?

Assertion: Refractive index of glass with respect to air is different for red light and violet light.
Reason: Refractive index of a pair of media depends on the wavelength of light used.

When one light ray is reflected from a plane mirror with $30^{\circ}$ angle of reflection, the angle of deviation of the ray after reflection is:

A biconvex lens of focal length 10cm is cut perpendicularly to principal axis. Then power of new lens

The respective angles of the flint and crown glass prisms are $A'$ and $A$. They are to be used for dispersion without deviation, then the ratio of their angles $A'/A$ will be

Statement I : Endoscopy involves use of optical fibres to study intemal organs.

Statement II : Optical fibres are based on the phenomenon of total internal reflection.

Assertion : If optical density of a substance is more than that of water than the mass density of substance can be less than water.

Reason : Optical density and mass density are not related.