Recent questions and answers in Ray optics and optical instruments

Why does a convex lens of glass $\mu = 1.5 $ behave as a diverging lens when immersed in carbon sulfide of $\mu= 1.65$?

answered May 25, 2016 by meena.p

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A magician during a show makes a glass lens $\mu = 1.5 $ disappears in a trough of liquid . What is the refractive index of the liquid ? Is the liquid water ?

answered May 25, 2016 by meena.p

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The sun (diameter d ) subtends an angle $\theta$ radian at the pole of a concave mirror of focal length f. What is the diameter of the image of the sun formed by the mirror ?

answered May 25, 2016 by meena.p

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A ray of light is incident at an angle of $60^{\circ}$ on a horizontal plane mirror. Through what angle should the mirror be titled to make the reflected ray horizontal ?

answered May 25, 2016 by meena.p

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What focal length should the reading spectacles have for a person whose near point is 50 cm ?

answered May 25, 2016 by meena.p

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One face of a prism is silvered and if refracting angle $30^{\circ}$ and refracting index 1.414 is silvered . At what angle must a ray of light fall on the silvered surface so that after refraction into prism and reflection at the silvered surface it retrace the path ?

answered May 25, 2016 by meena.p

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A convex and concave mirror each of radius 10 cm are placed facing each other and 15 cm apart. A point object is placed midway between them . Find the position of the final image if the reflection takes place at the concave mirror and then at the convex mirror .

answered May 25, 2016 by meena.p

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A point source kept at a distance of 1000 m has an illumination I. To change the illumination to 16 I the new distance should be

answered May 25, 2016 by meena.p

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Magnification power of an astronomical telescope for normal vision with usual notation is

answered May 25, 2016 by meena.p

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An eye specialist prescribe spectacles having combination of convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm . The power of this lens combination , in dioptre.

answered May 25, 2016 by meena.p

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A source exits sound of frequency 600 Hz inside water. The frequency heard in air (velocity of sound in water 1500 m/s velocity of sand in air 300 m/s) will be

answered May 25, 2016 by meena.p

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A substance has a critical angle of $45^{\circ}$ for yellow light. What is its refractive index ?

answered May 25, 2016 by meena.p

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A thin convex lens of focal length 25 cm is cut into two pieces 0.5 cm above the principal axis . The top part is placed at $(0,0) $ and an object at $(-50 cm, 0)$. Find the coordinate axis ?

answered May 25, 2016 by meena.p

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For a glass prism $(\mu=\sqrt 3)$ the angle of minimum deviation is equal to the angle of the prism . Find the angle of the prism .

answered May 25, 2016 by meena.p

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The immiscible liquids of densities $d_1 > d_2 > d_3$ and refractive indices $\mu_1 > \mu_2 > \mu_3$ are put in a beaker . The height of each liquid column is $\large\frac{h}{3}$. A dot is made at the bottom of the beaker . For near normal vision, find the apparent depth of the dot .

answered May 25, 2016 by meena.p

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An unsymmetrical double convex thin lens, forms the image of a point object on its axis will the position of the image change in the lens is reversed ?

answered May 25, 2016 by meena.p

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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 ?

answered May 25, 2016 by meena.p

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

answered 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

answered 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 ?

answered May 24, 2016 by meena.p

1 answer

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 ?

answered 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 ?

answered May 24, 2016 by meena.p

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

answered 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

answered 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 ?

answered May 24, 2016 by meena.p

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A passenger in an aeroplane shall

answered 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

answered 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

answered 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

answered May 24, 2016 by meena.p

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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 ?

answered May 24, 2016 by meena.p

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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 ?

answered May 24, 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 ?

answered 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 ?

answered 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 ?

answered 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)

answered 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 ?

answered 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 $(25 cm)$

answered 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 )

answered 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 ?

answered May 23, 2016 by meena.p

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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 ?

answered 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 ?

answered May 23, 2016 by meena.p

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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 ?

answered May 23, 2016 by meena.p

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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 ?

answered 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 ?

answered May 23, 2016 by meena.p

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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 ?

answered 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

answered 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 ?

answered 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 ?

answered 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

answered 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

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