... the apparent position of the coin. A coin placed at the bottom of a tank appears to be raised when water is poured into it. Carbon disulphide is more denser than the ethyl alcohol. On the other hand the shift in the image depends directly on the refractive index. Refractive index is least for red colour. A ray of light travelling in air enters obliquely into water. When the light ray is travelling in a glass emerging into air, the ray will bend away from the normal. The point from which the refracted rays appear to come gives the apparent position of the coin. The phenomenon is known as refraction of light. Q14. Objects appear 33% larger (which is 4/3 magnification), or 25% closer. The speed of light in substance X is 1.25×108m/s and that in air is 3×108m/s. Letter V will be raised maximum. When a pencil is placed in water, it appears to be bent because of the refraction of light. Q4. Fill in the following blanks with suitable words: a) Light travelling along a normal is ………. Following is the ray diagram of a beam of light travelling in air which is incident on water: Q5. Q13. A ray of light travelling in water emerges into air. Q38. Q15. Class objects are used as templates to create instance objects, which embody both the data (attributes) and code (methods) specific to a datatype. Similarly when the object is in the rarer medium and observer is in the denser medium it appears away from its original position and hence apparent height is more than that of the real height. Q2. We say that it is …………. Refractive indices of water, sulphuric acid, glass, and carbon disulphide are 1.33, 1.43, 1.53, 1.63 respectively. Due to which, the Sun appears to be slightly raised above the horizon and is visible 2 minutes before actual sunrise and 2 minutes after the actual sunset. What is the speed of light in a medium of refractive index 6/5 if its speed in air is 3,00,000 km/s? This is because refraction causes an apparent shift in the position of the part of the pencil within the water. Q6. Question 11: Name the phenomenon due to which a swimming pool appears less deep than it really is. b) If a ray of light is passing from glass into water, it will bend away from the normal. a) Explain why a stick half immersed in water appears to be bent at the surface. An object seen in the water will usually appear to be at a different depth than it actually is, due to the refraction of light rays as they travel from the water into the air. b) What is meant by the refractive index of a substance? The light travels slowest in: The correct answer is d) carbon disulphide. Glass has a higher refractive index than water. Refractive index is the ratio between the sine of the angle of incidence and the sine of the angle of refraction. The refractive indices of four materials A, B, C, and D are 1.33, 1.43, 1.71, and 1.52 respectively. If the refractive index of water is 4/3, find the actual depth of water in the tank. A ray of light travelling in air is incident on a rectangular glass block and emerges out into the air from the opposite face. Have a look at the picture. Refractive index of diamond = speed of light in air/speed of light in diamond. Q17. The speed of light in air is 3 × 108m/s. Why a coin placed at the bottom of a beaker containing water appears raised? Thus, for least rise μ should be least. Q25. What happens to the speed of light rays when they enter these materials? Q4. Answer: (a) The stick appears to be bent and raised up in place of BA as BA’ due to refraction of light on passing from denser medium (water) to rarer medium (air) No, the image of all letters will not be at the same place. A little more than 6 miles off the coast of Point Dume in Malibu, California, an unusual-looking structure sits on the sea bed floor. Q18. As the rays appear to come from a point above the coin, therefore, the coin seems io be raised. Q9. Q14. In which material do you think light rays travel faster: glass or air? An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At the surface of the water, the straw appears to be misaligned or broken; the portion of the straw above the water is shifted relative to the image viewed under the water. A ray of light travelling in air is incident on a parallel-sided glass slab. (The same happens in glass, and that’s how they make lenses.) What is meant by refraction of light? b) Refractive index of a substance is the speed of the light in the vacuum to the speed of the light in a medium. The angle of refraction will be: The correct answer is b) smaller than the angle of incidence. This means that more the optically denser medium, more will be the refraction of light rays. The light ray will bend towards the normal. The speed of light in air is 3.00×108m/s. According to Snell’s law, the ratio of sine of angle of incidence to the sine of angle of refraction is equal to the constant for a given pair of media. The speed of light in water is 2.25×108m/s. Following is the ray diagram: b) The phenomenon is known as refraction of light. c) Speed of light in air = 300 million m/s, Speed of light in water = 225 million m/s, We know that, refractive index of water = speed of light in air/speed of light in water. Also, the ratio between the sine of the angle of incidence and the sine of the angle of refraction is equal to a constant. Let OC be the ray coming from O which passes from water into air and gets refracted away from the normal. Fill in the following blank with a suitable word: When a ray of light goes from air into a clear material, you see the ray bend. Oscillopsia is a vision problem in which objects appear to jump, jiggle, or vibrate when they’re actually still. Q22. Air is a rarer medium and water is a denser medium whenever Light ray moves from rarer medium to the denser medium the ray bends towards normal. This means: A. the image is real and erect and the lens is a converging lens B. the image is real and inverted and the lens is a converging lens b) Show the lateral displacement of the ray on the diagram. A ray of light goes from water into air. b) Name the phenomenon due to which a pencil partly immersed in water and held obliquely appears to be bent at the water surface. – an object placed under water appears to be raised. A straw is placed with a diagonal orientation within a half-filled beaker of water. Here as the object is immersed then the rays from the object is refracted from the denser medium to the air ( rarer) medium and the … Which is optically denser? Why does a ray of light bend when it travels from one medium to another? This happens due to the presence of buoyant force or upthrust.Buoyant force is a force exerted by liquid against gravity on the object that is completely submerged in it.Another factor that can be can be considered is density...if the density of the object is more than that of water that is more than 1000Ro then it will sink... otherwise it will float above water. On entering water it slows down to 225 million m/s. Light enters from air to diamond which has a refractive index of 2.42. A stone placed at the bottom of a water tank appears raised by 80 cm. In medium X its speed is 2 × 108m/s and in medium Y the speed of light is 2.5 × 108m/s. Q33. Q2. Refraction of light is the phenomenon that makes the water to appear shallower than it really is. Q20. this is because of the phenomenon of refraction. The angle of refraction will be: The correct answer is b) greater than the angle of incidence. An object seen in the water will usually appear to be at a different depth than it actually is, due to the refraction of light rays as they travel from the water into the air. Draw a labelled ray diagram to show the refraction of light. A beam of light travelling in air is incident on water. What name is given to the ratio of sine of angle of incidence to the sine of angle of refraction? When the light rays enter these materials their speed reduces. Light travels more quickly through water than through glass. When the light rays pass from air into these materials, they refract the maximum in: Q21. When a light ray passes from air into glass, what happens to its speed? The final direction of the ray of light will be the same as the incident direction. OD is the second ray that gets refracted along with DY. Q12. The speed of light in vacuum and in two different glasses is given in the table below: a) Calculate the absolute refractive indexes of flint glass and crown glass. Answer. When the light rays pass from water into glass, they bend towards the normal. A coin placed at the bottom of a tank appears to be raised when water is poured into it. An erect object is placed on the central axis of a thin lens, further from the lens than the magnitude of its focal length. If a ray of light goes from a denser medium to rare medium, will it bend towards the normal or away from the normal? Calculate the speed of light in glass. The ratio of sine of angle of incidence to the sine of angle of refraction is known as refractive index. Ltd. All rights reserved. ... why should you never raise the stage toward the objective with the coarse adjustment while looking through the ocular. 12) When an object is placed on the left at ∞ (very far) from a converging lens, its image forms on the right (a) at F. (b) at 2F. b) Calculate the relative refractive index for light going from crown glass to flint glass. (c) between F and 2F. 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