HARD
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Water inside rises by 10 cm above the water surface in a small capillary tube of radius 0.5 mm. The angle of contact is 60o due to some impurity which does not affect density or refractive index ( μ=43). If a small particle is suspended y cm under the water meniscus, then a virtual image is formed 311 cm from the meniscus, when viewed from the top of the capillary. Hence 'y' is?

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Important Questions on Ray Optics

HARD
A plano-convex lens is made of a material of refractive index n. When a small object is placed 30 cm away in front of the curved surface of the lens, an image of double the size of the object is produced. Due to reflection from the convex surface of the lens, another faint image is observed at a distance of 10 cm away from the lens. Which of the following statement(s) is (are) true?
MEDIUM

A light ray enters a solid glass sphere of refractive index μ=3 at an angle of incidence 60°. The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is:

MEDIUM
A concave glass lens of refractive index 1.5 is immersed in carbon di-sulfide (refractive index =1.6). Which of the following is true?
[ Assume both surfaces of the lens have same radius of curvature =R]
HARD
An object approaches a convergent lens from the left of the lens with a uniform speed 5 m s-1 and stops at the focus, the image
MEDIUM
Diameter of a plano - convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of lens is 2×108 m s-1, the focal length of the lens is:
EASY

In the shown situation, if middle portion of the lens is painted black, then

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HARD

A beaker of radius r is filled with waterrefractive index 43 up to a height H as shown in the figure on the left. The beaker is kept on a horizontal table rotating with angular speed ω. This makes the water surface curved so that the difference in the height of water level at the centre and at the circumference of the beaker is hhH, hr, as shown in the figure on the right. Take this surface to be approximately spherical with a radius of curvature R. Which of the following is/are correct? (g is the acceleration due to gravity)

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HARD

Consider the following statements regarding the real images formed with a converging lens.
(I) Real images can be seen only if the image is projected onto the screen
(II) The real image can be seen only from the same side of the lens as that on which the object is positioned.
(III) Real images produced by converging lenses are not only laterally but also longitudinally inverted as with mirrors.

Which of the above statement/statements is/are incorrect?

EASY
There is a small air bubble at the centre of a solid glass sphere of radius r and refractive index μ. What will be the apparent distance of the bubble from the centre of the sphere, when viewed from outside?
MEDIUM
Two identical glass rods S1 and S2 (refractive index = 1.5) have one convex end of radius of curvature 10 cm. They are placed with the curved surfaces at a distance d as shown in the figure, with their axes (shown by the dashed line) aligned. When a point source of light P is placed inside rod S1 on its axis at a distance of 50 cm from the curved face, the light rays emanating from it are found to be parallel to the axis inside S2 . The distance d is

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HARD

A converging mirror is placed on the right hand side of a converging lens as shown in the figure. The focal length of the mirror and the lens are 20 cm and 15 cm respectively. The separation between the lens and the mirror is 40 cm and their principal axes coincide. A point source is placed on the principal axis at a distance d to the left of the lens. If the final beam comes out parallel to the principal axis, then the value of d is:

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MEDIUM

A parallel beam of light strikes a piece of transparent glass having cross section as shown in the figure below. Correct shape of the emergent wavefront will be (figures are schematic and not drawn to scale)

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HARD

A point object is placed on the axis of a thin convex lens of focal length 0.05 m at a distance of 0.2 m from the lens and its image is formed on the axis. If the object is now made to oscillate along the axis with a small amplitude of A cm, then what is the amplitude of oscillation of the image?

[you may assume, 11+x1-x, where x1
 

HARD
A diverging lens with magnitude of focal length 25 cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm. A beam of parallel light falls on the diverging lens. The final image formed is:
HARD
A thin convex lens is placed just above an empty vessel of depth 80 cm. The image of a coin kept at the bottom of the vessel is thus formed 20 cm above the lens. If now water is poured in the vessel upto a height of 64 cm what will be the approximate new position of the image? Assume that refractive index of water is 4/3.
MEDIUM
An object is moving with a velocity of 0.01 m s-1 towards a convex lens of focal length 0.3 m. The magnitude of the rate of separation of an image from the lens when the object is at a distance of 0.4 m from the lens is
HARD
The same size images are formed by a convex lens when the object is placed at 20 cm or at 10 cm from the lens. The focal length of convex lens is
HARD

A transparent thin film of uniform thickness and refractive index n1=1.4 is coated on the convex spherical surface of radius R at one end of a long solid glass cylinder of refractive index n2=1.5 , as shown in the figure. Rays of light parallel to the axis of the cylinder traversing through the film from air to glass get focused at distance f1 from the film, while rays of light traversing from glass to air get focused at distance f2 from the film. Then

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MEDIUM
The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is,
HARD
The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of the cornea (7.8 mm). This surface separates two media of refractive indices 1 and 1.34. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus.