Ray optics practice · Medium

Microscope is an optical instrument which

Pick the wrong answer in the context with rainbow.

A thin prism of angle $15^\circ$ made of glass of refractive index ${\mu _1} = 1.5$ is combined with another prism of glass of refractive index ${\mu _2} = 1.75$. The combination of the prisms produces dispersion without deviation. The angle of the second prism should be

A screen is placed $90\, {~cm}$ from an object. The image of an object on the screen is formed by a convex lens at two different locations separated by $20\, {~cm}$. The focal length of the lens is

Assertion: For observing traffic at our back, we prefer to use a convex mirror.

Reason: A convex mirror has a much larger field of viwe than a plane mirror or a concave mirror.

Different objects at different distances are seen by the eye. The parameter that remains constant is

Astigmatism (for a human eye) can be removed by using

A beam of white light is incident on a convex lens. Which of the following is the correct relation between the focal length for red light $\left(f_R\right)$ and that of violet light $\left(f_V\right)$ ?

A slide projector has to project a $35 \mathrm{~mm}$ slide $(35 \mathrm{~mm} \times 23 \mathrm{~mm})$ on a $2 \mathrm{~m} \times 2 \mathrm{~m}$ screen at a distance of $10 \mathrm{~m}$ from the lens. What should be the focal length of the lens in the projector?

From which source a continuous emission spectrum and a line absorption spectrum are simultaneously obtained

In a refracting astronomical telescope, the final image is

A thin glass lens of refractive index 1.5 has optical power of –4 D in air. Its optical power in a liquid medium having refractive index 1.6 will be

Assertion: Angle of deviation depends on the angle of prism.
Reason: For thin prism $\delta=(\mu-1) \mathrm{A}$, Where $\delta=$ angle of deviation $\mu=$ refractive index, $\mathrm{A}=$ angle of prism

A person’s near point is $50\,\,cm$ and his far point is $3\,\,m$. Power of the lenses he requires for
(i) reading and
(ii) for seeing distant stars are

Dispersive power depends upon

Speed of light is maximum in

In a simple microscope, if the final image is located at infinity then its magnifying power is

A light ray, going through a prism with the angle of prism $60^{\circ}$, is found to deviate by $30^{\circ}$. What limit on the refractive index can be put from these data?

If the refractive indices of crown glass for red, yellow and violet colours are $\mathrm{1}\mathrm{.5140, 1}\mathrm{.5170}\,\mathrm{ and }\,\mathrm{1}\mathrm{.5318}$ respectively and for flint glass these are $\mathrm{1}\mathrm{.6434,}\,\,\mathrm{1}\mathrm{.6499}\,\mathrm{ and }\,\mathrm{1}\mathrm{.6852}$ respectively, then the dispersive powers for crown and flint glass are respectively

An achromatic combination of lenses produces

Which of the following is used in optical fibres

On heating a liquid, the refractive index generally

When light travels from one medium to the other of which the refractive index is different, then which of the following will change

Statement-A: The minimum distance between an object and its real image formed by a convex lens is $2{f}$.

Statement-B: The distance between an object and its real image is minimum when its magnification is -1.

A person is suffering from hypermetropia and use lens of +1D if due to ageing its accommodation power also decreases by + 2D. Where will his near point without spects:

The image of a virtual object formed by a concave mirror

Assertion: Light from an object falls on a concave mirror forming a real image of the object. If both the object and mirror are immersed in water, there is no change in position of the image.

Reason: The formation of image by reflection does not depend on surrounding medium., so there is no change in position of image.

The astronomical telescope consists of objective and eye-piece. The focal length of the objective is

Assertion: When an object is placed between two plane parallel mirrors, then all the images found are of equal intensity.

Reason: In case of plane parallel mirrors, only two images are possible.

How many images are formed by the lens shown, if an object is kept on its axis?