Ray optics practice · Medium

Assertion : In bright light camera with high f no. must be used.

Reason : As f no. increases the aperture size decreases.

In a microscope orange light is used for resolution. The resolving power of microscopes can be increased by using

A concave mirror forms the image of an object on a screen. If the lower half of the mirror is covered with an opaque card, the effect would be to make the

Two thin lenses whose powers are $+ \,2\,D$ and $- \,4\,D$ respectively combine, then the power of combination is

The angle of incidence for a ray of light at a refracting surface of a prism is ${45^\mathrm{o}}$. The angle of prism is ${60^\mathrm{o}}$ . If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are:

Four lenses A, B, C and D power $+ \,100\,D,\, - 50\,D,\,20\,D$ and 5D. Which lenses will you use to design a compound microscope for best magnification?

A person can see objects clearly placed beyond 1m. Power of lens required to correct defect will be:-

The images of clouds and trees in water always less bright than in reality –

A small object is placed at a distance of $3.6 \mathrm{~cm}$ from a magnifier of focal length $4.0 \mathrm{~cm}$. (a) Find the position of the image. (b) Find the linear magnification. (c) Find the angular magnification.

Assertion: Convergent lens property of converging remains same in mediums.
Reason: Property of lens whether the ray is diverging or converging depends on the surrounding medium.

A convergent lens of power 16D is used as a simple microscope. The magnification produced by the lens, when the final image is formed at least distance of distinct vision is

If a parallel beam of white light is incident on a converging lens, the colour which is brought to focus nearest to the lens is

A square wire frame of side $3.0 \mathrm{~cm}$ is placed $25 \mathrm{~cm}$ away from a concave mirror of focal length $10 \mathrm{~cm}$. The centre of the wire frame is on the axis of the mirror, with its two sides normal to the mirror. The area enclosed by the image of the wire frame is -

${f_v}$ and ${f_r}$ are the focal lengths of a convex lens for violet and red light respectively and ${F_v}$ and ${F_r}$ are the focal lengths of a concave lens for violet and red light respectively, then

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction.

Reason R: The wavelengths of waves are different in different media.

In the light of the above statements, choose the most appropriate answer from the options given below

Monochromatic light of frequency $5\,\, \times \,\,{10^{14}}\,\,\mathrm{Hz}$ travelling in vaccum enters a medium of refractive index $\mathrm{1}\mathrm{.5}$. It wavelength in the medium is

If the lower half of a concave mirror’s reflecting surface is made opaque, which of the following statements describe the image of an object placed infront of the mirror

$\mathrm{S1}$: Intensity of the image will increase

$\mathrm{S2}$: The image will show only half of the object

$\mathrm{S3}$: No change in the image

$\mathrm{S4}$: Intensity of the image will be reduced to half

A particle is projected above a plane mirror. Taking up as positive and down as negative. Mark the correct options:

A thin glass lens $(\mu=1.5)$ of focal length $15 \mathrm{~cm}$ is kept inside water $\left(\mu=\frac{4}{3}\right)$. The new focal length of lens in water is

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.