Ray optics practice · Mixed difficulty

Assertion: The setting sun appears to be red.

Reason: Scattering of light is directly proportional to the wave length.

When a glass lens with $n = 1.47$ is immersed in a trough of liquid, it looks to be disappeared. The liquid in the trough could be

What causes chromatic aberration?

Assertion: Just before setting, the sun may appear to be elliptical. This happens due to refraction.

Reason: Refraction of light ray through the atmosphere may cause different magnification in mutually perpendicular directions.

A plane wave of sound travelling in air is incident upon a plane water surface. The angle of incidence is $60^{\circ}$. If velocity of sound in air and water are $330 \mathrm{~m} / \mathrm{s}$ and $1400 \mathrm{~m} / \mathrm{s}$, then the wave undergoes

A beam of light of width $t$ is incident on an air-water boundary at an angle of incidence $45^{\circ}$. The width of the beam in water is (Refractive index of water $=\mu$):

Assertion: In ionospheric reflection, phase change does not occurs with the light wave.
Reason: The ionosphere reflection is similar to the total internal reflection which is similar to the total internal reflection in miraj

A convex lens is immersed in a liquid, whose refractive index is equal to the refractive index of the material of the lens. Then its focal length will

How does the angle of minimum deviation of a glass prism vary, if the incident violet light is replaced with red light?

The frequency of a light ray is $6\,\, \times \,\,{10^{14}}\,\,Hz$. Its frequency when it propagates in a medium of refractive index $\mathrm{1}\mathrm{.5}$, will be

Two thin lens have a combined power of $10 \mathrm{D}$ in contact. When separated by $20 \mathrm{~cm}$ their equivalent power is $6.25 \mathrm{D}$. Find their in dividual powers in dioptres -

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