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प्रश्न
A straight stick partly dipped in water obliquely appears to be bent at the surface of the water.
A rod immersed partially and obliquely in water appears to be bent. Explain.
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उत्तर १
The phenomenon is due to refraction of light.
A ray of light OC coming from O passes from water into air and is refracted away from normal (along CX). Another ray, OD, gets refracted along with DY. The two refracted rays CX and DY, when produced backwards, appear to meet at the point I. Thus, I is the virtual image of the end O of the stick. Therefore, the stick appears to be bent as shown below.
उत्तर २
- Light Refraction: When light passes from one medium (e.g., water) to another (e.g., air), it changes speed and direction. Light rays traveling from the submerged part of the stick (in water) to the observer's eyes (in air) bend away from normal at the water’s surface.
- Apparent Bending: Due to this bending of light, the part of the stick underwater appears shifted upward. As a result, the stick seems bent at the surface of the water, even though it is straight.
संबंधित प्रश्न
A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?
A student focused the Sun rays using an optical device 'X' on a screen S as shown.
From this it may be concluded that the device 'X' is a (select the correct option)
(A) Convex lens of focal length 10 cm.
(B) Convex lens of radius of curvature 20 cm.
(C) Convex lens of focal length 20 cm.
(D) Concave mirror of focal length 20 cm.
An image that cannot be obtained on a screen is called ______.
We can obtain an enlarged and erect image by a convex mirror.
The letter F is placed in front of a plane mirror:
What is the name of the phenomenon involved?
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
Why is a hole burnt in the carbon paper?
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
At which point of the spherical mirror the carbon paper is placed?
A small object is placed 150 mm away from a diverging lens of focal length 100 mm.
(i) Copy the figure below and draw rays to show how an image is formed by the lens.
Figure
(ii) Calculate the distance of the image from the lens by using the lens formula.
A coin placed at the bottom of a vessel appears to be raised when water is poured in the vessel.
AB and CD, two spherical mirrors, from parts of a hollow spherical ball with its centre at O as shown in the diagram. If arc AB = `1/2` arc CD, what is the ratio of their focal lengths? State which of the two mirrors will always form virtual image of an object placed in front of it and why.
Name the spherical mirror which (i) diverges (ii) converges the beam of light incident on it. Justify your answer by drawing a ray diagram in each case.
Name the mirror which always produces an erect and virtual image. How is the size of image related to the size of object?
Write the spherical mirror's formula and explain the meaning of each symbol used in it.
State two uses of a concave mirror.
The image formed by a convex mirror is of size one third the size of object. How are u and v related?
Define the term Aperture.
Define the term Centre of curvature.
