Recent questions tagged ncert

The near vision of an average person is 25 cm . To view an object with an angular magnification of 10, What should be the power of the microscope ?

asked May 25, 2016 by meena.p

1 answer

Will the focus length of a lens for red light be more , same or less than that for blue light ?

asked May 24, 2016 by meena.p

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An astronomical refractive telescope has an objective of focal length 20 m and eye piece of focal length 2 cm

asked May 24, 2016 by meena.p

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A car is moving with a constant speed of 60 km/hr on a straight road. Looking at the rear view mirror the driver finds that the car following him is at a distance of 100 m and is approaching with a speed of 5 km/hr. In order to keep track of the car in the rear, the driver begins to glance alternatively at the rear and side mirror of his car, after every 2s till the other car overtakes. If the two cars maintaining the speed , which of the following statement is /are correct ?

asked May 24, 2016 by meena.p

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The optical density of turpentine is higher than that water , while its mass density is lower a layer a tuperline floating over water in a container . For which one of the four rays incident on turpentine the path shown is correct ?

asked May 24, 2016 by meena.p

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The direction of ray of light incident on a concave mirror by PQ while direction in which the ray would travel after reflection four ray marked 1,2,3 and 4 . Which of the four rays correctly shown the direction of reflected ray ?

asked May 24, 2016 by meena.p

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The phenomenon involved in the reflection of radio- waves by ionosphere is similar to

asked May 24, 2016 by meena.p

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The radius of culvature of the curved surface of a plano - convex lens is 20 cm . If the refractive index of the material of the lens be 1.5 , it will

asked May 24, 2016 by meena.p

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You are given four sources of light each one providing a light of a single colour - red, 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 incident ?

asked May 24, 2016 by meena.p

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A passenger in an aeroplane shall

asked May 24, 2016 by meena.p

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An object approaches a convergent lens from the left of the lens with a uniform speed 5 m/s and stops at the focus . The image

asked May 24, 2016 by meena.p

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

asked May 24, 2016 by meena.p

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A ray of light incident at an angle $\theta$ on an refracting face of a prism emerge from the other face normally . If the angle of the prism is 5 and the prism is made of a material of refractive index 1.5 , the angle of incident is

asked May 24, 2016 by meena.p

1 answer

Light incident normally on a plane mirror attached to a galvanometer coil retraces backwards .A current in the coil produces a defection of $35^{\circ}$ of the mirror . What is the displacement of the reflected spot of light on ascreen 1.5 m away ?

asked May 24, 2016 by meena.p

1 answer

A carsegrainian telescope user two mirrors such a telescope is built with the mirrors 20 mm apart. If the radius of curvature of large mirror is $220\;mm$ and the small mirror is 140 mm, where will the find image of the object at infinity be ?

asked May 23, 2016 by meena.p

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A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity ). What is the height of the final image of the tower if it is formed at 25 cm ?

asked May 23, 2016 by meena.p

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A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity ).If this telescope is used to view a 100 cm tall tower 3 km away , what is the height of the image of the tower formed by the objective lens ?

asked May 23, 2016 by meena.p

1 answer

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity ) What is the seperation between the objective lens and eyepiece ?

asked May 23, 2016 by meena.p

1 answer

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity )When the final image is formed at the least distance of distinct vision (25 cm)

asked May 23, 2016 by meena.p

1 answer

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the seperation between the objective lens and the eye piece ?

asked May 23, 2016 by meena.p

1 answer

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity ) When the final image is formed at the least distance of distinct vision $(25 cm)$

asked May 23, 2016 by meena.p

1 answer

A small telescope has an objective lens of focal length 140 cm and eyepiece of focal length 5.0 cm What is the magnifying power of telescope for viewing distant objects when the telescope is in normal adjustment (ie When the final image is at infinity )

asked May 23, 2016 by meena.p

1 answer

An angular magnification (magnifying power ) of 30 x is desired using an objective of focal length 1.25 cm and an eye piece of focal length 5 cm. How will you set up the compound microscope ?

asked May 23, 2016 by meena.p

1 answer

When viewing through a compound microscope our eyes should be positioned not on the eye piece, but a short distance away from it for best viewing , why ? How much should be the short distance between the eye and the eyepiece ?

asked May 23, 2016 by meena.p

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Why must both the objective and eyepiece of a compound microscope have short focal length ?

asked May 23, 2016 by meena.p

1 answer

Magnifying power of simple microscope is inversely proportional to the focal length of the lens . What then stops us from using a convex lens of smaller focal length and achieve greater and greater magnifying power ?

asked May 23, 2016 by meena.p

1 answer

In viewing through a magnifying glass, one usually position one's eye very close to the lens , Does angular magnification change if the eye is moved back ?

asked May 23, 2016 by meena.p

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The angle subtended at the eye by an object is equal to the angle subtended at the eye by the virtual image produced by the magnifying lens. In what sense does a magnifying glass provided angular magnification ?

asked May 23, 2016 by meena.p

1 answer

What should be the distance between the object and magnifying glass (converging lens of focal length 10 cm) if the virtual image of each square is to have an area of $6.25 mm^2$, would you be able to see the square distinct with your eyes very close to magnifier ?

asked May 23, 2016 by meena.p

1 answer

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held close to the eye. At what distance should the lens be held from the card sheet in order to view the squares distinct with the minimum possible magnifying power ? Is the magnification equal to the magnifying power in this case ? explain

asked May 20, 2016 by meena.p

1 answer

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held close to the eye. At what distance should the lens be held from the card sheet in order to view the squares distinct with the minimum possible magnifying power ? What is the magnification in this car ?

asked May 20, 2016 by meena.p

2 answers

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held close to the eye. At what distance should the lens be held from the card sheet in order to view the squares distinct with the minimum possible magnifying power ?

asked May 20, 2016 by meena.p

1 answer

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held . close to the eye. Is the magnification same as the magnifying power ? explain

asked May 20, 2016 by meena.p

1 answer

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held . close to the eye. What is the angular magnification produced by the lens ?

asked May 20, 2016 by meena.p

1 answer

A card sheet divided into squares each of size $1\; mm^2$ is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held . close to the eye. What is the magnification produced by the lens ? How much is the area of each square in the virtual image ?

asked May 20, 2016 by meena.p

1 answer

A man with normal near point (25 cm) reads a book with small print using a magnifying glass a thin convex less of focal length 5 cm what are the closest and farthest distance at which he can read the book , When viewing through the magnifying glass? What is the maximum and the minimum angular magnification possible using the above simple microscope ?

asked May 20, 2016 by meena.p

1 answer

A man with normal near point (25 cm) reads a book with small print using a magnifying glass a thin convex less of focal length 5 cm what are the closest and farthest distance at which he can read the book , When viewing through the magnifying glass?

asked May 20, 2016 by meena.p

1 answer

A person looking at a person wearing a shirt with a pattern comprising vertical and horizontal lines is able to see the vertical lines more distinctly than the horizontal lines . what is the defect due to ? How is such a defect of vision corrected ?

asked May 18, 2016 by meena.p

1 answer

A muopic person has been using spectacles of power -1.0 D for distant vision . During old age , he also needs to use separate reading glasses of power +2.0 D. Explain what may have happened ?

asked May 18, 2016 by meena.p

1 answer

Does short sighted ness (myopia) or long sightedness imply necessarily that the eye has partially lost its ability of accommodation ? If not what might cause these defects of vision ?

asked May 18, 2016 by meena.p

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For a normal eye, the far point is at infinity and the near point of distinct vision is about 25 cm in front of the eye. The cornea of the eye provides a converging power of about 40 diepter and the least converging power of eye lens behind the cornea is about 20 dioptre. From this rough data, estimate the range of accommodation of normal eye .

asked May 18, 2016 by meena.p

1 answer

You are given prisms made of crown glass and flint glass with a wide variety of angles. suggest a combination of prism which will deviate a pencil of white light with out much dispersion . which will displace a pencil of white light with out much deviation .

asked May 18, 2016 by meena.p

1 answer

You are given prisms made of crown glass and flint glass with a wide variety of angles. suggest a combination of prism which will deviate a pencil of white light with out much dispersion .

asked May 17, 2016 by meena.p

1 answer

At what angle should a ray of light be incident on the face of a prism of refracting angle $60^{circ}$ , So that it just suffers total internal reflection at the other face ? The refractive index of the prism is $1.524$

asked May 17, 2016 by meena.p

1 answer

An object 1.5 cm in placed on the side of the convex lens, where two lenses of focal lengths 30 cm and 20 cm are placed 8.0 cm apart with their principle axis coincident . The distance between the object and the convex lens is 40 cm. Determine the magnification produced by two lens system and size of the image

asked May 17, 2016 by meena.p

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Determined the effective focal length of the combination of two lenses of focal length 30 cm and 20 cm if they are placed 8.0 cm apart with their principal axes coincident. Does the answer depend on which side a beam a parallel light is incident ? Is the motion of effective focal length of system useful at all ?

asked May 17, 2016 by meena.p

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A screen is placed 90 cm from an object . The image of the object is formed by a convex lens at two different location separated by 20 cm. Determined the focal length of the lens .

asked May 17, 2016 by meena.p

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The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3 m away by means of a large convex lens . What is the maximum possible focal length of the lens required for the prupose?

asked May 17, 2016 by meena.p

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The refractive index of diamond is much greater than that of ordinary glass. Is this fact of some use to diamond cutter ?

asked May 17, 2016 by meena.p

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Does the apparent depth of a tank of water change if viewed obliquely ? If so does the apparent depth increase or decrease ?

asked May 17, 2016 by meena.p

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