Ray optics practice · Medium

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

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.

$P$ is a point on the axis of a convex mirror. The image of $P$ formed by the mirror, coincides with $P$. A rectangular glass slab of thickness $t$ and refractive index $\mathrm{\mu }$ is now introduced between $P$ and the mirror. For the image of P to coincide with $P$ again, the mirror must be moves

Two thin lenses of focal length $\mathrm{20}\,\,\mathrm{cm}$ and $\mathrm{25}\,\,\mathrm{cm}$ are placed in contact .The effective power of the combination is

The deviation produced by a prism is

An astronaut in a spaceship see the outer space as

In the position of minimum deviation when a ray of yellow light passes through the prism, then its angle of incidence is

White light is incident on one of the refracting surfaces of a prism of angle $5^\circ$. If the refractive indices for red and blue colours are $\mathrm{1}\mathrm{.641}$ and $\mathrm{1}\mathrm{.659}$ respectively, the angular separation between these two colours when they emerge out of the prism is

If there had been one eye of the man, then

Three prisms $\mathrm{1, 2 }\,\mathrm{and\,3}$ have the prism angle $A = {60^0}$, but their refractive indices are respectively $\mathrm{1}\mathrm{.}\,\mathrm{4, 1}\mathrm{.}\,\mathrm{5 }\,\mathrm{and}\,\mathrm{ 1}\mathrm{.}\,\mathrm{6}$. If ${\delta _1},\,\,{\delta _2},\,\,{\delta _3}$ be their respective angles of deviation then

When a plane mirror is rotated through an angle $\theta$ then the reflected ray turns through the angle $2\,\theta$ then the size of the image

If a thin prism of glass is dipped into water then minimum deviation (with respect to air) of light produced by prism will be left $\left( {_a{\mu _g} = \frac{3}{2}\,\,\mathrm{and}\,{\,_a}{\mu _w} = \frac{4}{3}} \right)$

A short pulse of white light is incident from air to a glass
slab at normal incidence. After travelling through the slab,
the first colour to emerge is

A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black, the image will

Assertion: A reflecting type of telescope is preferred over refracting type in astronomy.
Reason: A reflecting type of telescope is free from chromatic aberration and spherical aberration.