Ray optics practice · Mixed difficulty

Mimimum distance between object and image formed by concave mirror of focal length $f$ can be:

Assertion (A): Formation of mirages in hot deserts is a phenomenon of total internal reflection.

Reason (R): Air close to the land is hotter than the air far from the land in a hot desert. So total internal reflection takes place.

The total distance travelled by light in one year is known as

In a converging lens as a magnifying glass, the object must be placed

The passenger side-view mirror on an automobile often has the notation. "Objects seen in mirror are closer than they appear". Is the image really farther away than the object?

If in denser medium, incidence angle is equal to critical angle, then refraction angle will be

Which of the following spectrum have all the frequencies from high to low frequency range

The minimum required size of plane mirror to visualize complete image of an object is

Two thin convex lenses of focal lengths $f_1$ and $f_2$ are placed at a distance $d.$ For the power of the combination to be zero, then separation $d$ should be equal is:

Show that the angle of minimum deviation produced by a thin prism is reduced to one-fourth (with respect to air) when it is immersed in water. Given ${ }^a \mu_g=3 / 2$ and ${ }^a \mu_w=4 / 3$.

A plano convex lens is made of glass of refractive index $\mathrm{1}\mathrm{.5}$. The radius of curvature of its convex surface is R. Its focal length is

Assertion : When we see the image in water, blurred image is seen.

Reason : Refractive index of air and water are different.

The relation between the linear magnification $m$, the object distance $u$ and the focal length $f$ is

A professor reads a greeting card received on his 50th birthday with $+2.5\,\mathrm{D}$ glasses keeping the card $25 \mathrm{~cm}$ away. Ten years later, he reads his farewell letter with the same glasses but he has to keep the letter $50 \mathrm{~cm}$ away. What power of lens should he now use?

Under which of the following conditions will a convex mirror of focal length $f$ produce an image that is erect, diminished and virtual

An object $2.4\,m$ in front of a lens forms a sharp image on a film $12\,\,cm$ behind the lens. A glass plate $1\,\,cm$ thick, of refractive index $\mathrm{1}\mathrm{.50}$ is interposed between lens and film with its plane faces parallel to film. At what distance (from lens) should object shifted to be in sharp focus on film

Statement(A) : The Sun is visible a little
before the actual sunrise and until a little
after the actual sunset due to refraction of
light through the atmosphere.

Statement(B) : Mass density of
'Turpentine' is less than that of water but its
optical density is higher.

Assertion: An object is placed at a distance of $f$ from a convex mirror of focal length $f$ its image will form at infinity.
Reason: The distance of image in convex mirror can never be infinity.
In above question a statement of assertion is followed by statement of reason mark the correct choice.

The cladding material of optical fibre has refractive index

Continuous emission spectrum is produced by

Assertion: A plane mirror reflects a beam of light to form a real image for real object.

Reason: The incidence beam should be convergent to form real image.

A ray of light is incident at an angle of incidence of $60^{\circ}$ on the face of a prism having prism angle of $30^{\circ}$. The ray emerging out of the prism makes an angle of $30^{\circ}$ with the incident ray. The refractive index of material of prism is

The exposure time of a camera lens at the $\frac{f}{{2.8}}$ setting is $\frac{1}{{200}}$ second. The correct time of exposure at $\frac{f}{{5.6}}$ is

The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index $\mathrm{1}\mathrm{.5}$ and has a focal length $\mathrm{10}\,\,\mathrm{cm}$ in air. The lens is cut into two equal halves along a plane perpendicular to its principle axis to yield two plano-convex lenses. The two pieces are glued such that the convex surfaces touch each other. If this combination lens is immersed in water (refractive index $\mathrm{ = 4}\,\mathrm{/}\,\mathrm{3}$), its focal length (in cm) is

If the focal length of the objective lens is increased then

If the focal length of a double convex lens for red light is ${f_R}$, its focal length for the violet light is

For a compound microscope, the focal lengths of object lens and eye lens are ${f_0}$ and ${f_e}$ respectively, then magnification will be done by microscope when

Assertion : Refractive index of cold air is greater then that of hot air.

Reason : The molecules of cold air have lower thermal velocity.

Statement-I: The twinkling of star is due to reflection of light.

Statement-II: The velocity of light changes while going from one medium to the other.

A lens of large focal length and large aperture is best suited as an objective of an astronomical telescope since