Advertisements
Advertisements
प्रश्न
What is refraction of light?
What is refraction of light? Explain with the help of an example.
Explain the refraction of light.
Advertisements
उत्तर
- Light changes its direction when going from one transparent medium to another transparent medium. This change in direction is called the refraction of light.
- For example, the coin appears to disappear in a vessel when viewed from a specific angle. But as soon as the water is poured into the vessel at a certain level, the coin appears. This phenomenon is because light rays coming from the coin emerge out of the water and change their direction due to the refraction of light.
संबंधित प्रश्न
| Column I | Column II | Column III | |
| 1 | Dispersion | Long-sightedness | Twinkling of stars |
| 2 | Refraction | Splitting of white light into component colours | Convex lens |
| 3 | Hypermetropia | Change in the direction of the ray of light due to change in medium | Spectrum of seven colours |
Name the phenomenon responsible for the following effect:
When we sit in front of a plane mirror and write with our right hand, if appears in the mirror that we are writing with the left hand.
If an object is placed at a distance of 10 cm in from of a plane mirror, how far would it be from its image?
Which property of light makes a pencil cast a shadow when it is held in front of a light source?
Fill in the following blank with a suitable word:
When light is reflected, the angles of incidence and reflection are ............ .
A ray of light strikes a plane mirror such that its angle of incidence is 30°. What angle does the reflected ray make with the mirror surface?
What is lateral inversion? Explain by giving a suitable example.
Write the word AMBULANCE as it would appear when reflected in a plane mirror. Why is it sometimes written in this way (as its mirror image) on the front of an ambulance?
What is the difference between regular reflection of light and diffuse reflection of light?
An extended object in the form of an arrow pointing upward has been placed in front of a plane mirror. Draw a labelled ray-diagram to show the formation of its image.
State the uses of plane mirrors.
Write all the capital letters of the alphabet which look the same in a plane mirror.
The image formed by a plane mirror is :
(a) virtual, behind the mirror and enlarged.
(b) virtual, behind the mirror and of the same size as the object.
(c) real, at the surface of the mirror and enlarged.
(d) real, behind the mirror and of the same size as the object.
A man sits in an optician's chair looking into plane mirror which is 2 m away from him and views the image of a chart which faces the mirror and is 50 cm behind his head. How far away from his eyes does the chart appear to be?
A ray of light strikes a plane mirror PQ at an angle of incidence of 30°, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is ______.
Explain how to read the following message which was found on some blotting paper:
If a ray of light goes form a denser medium to a rarer medium, will it bend towards the normal or away from the normal?
When a ray of light passes from air into glass, is the angle of refraction greater than or less than the angle of incidence?
When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.
Water is optically denser than glass.
Light travels at a lower speed in water than in air.
When a ray of light travels from water to air, it bends ............. the normal.
Match the Following
| Column A | Column B |
| (a) white Light | (1) Convex mirror |
| (b) Refraction | (2) Concave mirror |
| (c) Virtual images | (3) refraction |
| (d) Real images | (4) spectrum |
| (e) Prism | (5) ray of light from glass to air |
What is the cause of refraction of light when it passes from one medium to another?
Fill in the blank and Explain the completed sentences.
The change in ______ of light rays while going from one medium to another is called refraction.
List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to `1/3` rd of its size . Find the distance of the object from the optical centre of the lens .
List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.
Light changes its direction when going from one transparent medium to another transparent medium. This is called _______.
Write scientific reason.
The sun appears on the western horizon for some time after sunset.
Write scientific reason.
The coin disappears in a vessel as it is seen from a specific location. But as soon as the water is poured into the vessel to a certain level, the coin appears.
Observe the given figure and name the following.
| Ray AB | |
| Ray NM | |
| Ray MD | |
| ∠ r |
Observe the given figure and write appropriate phenomenon of light in the box.
Explain the working of a periscope.
Explain with diagrams how refraction of incident light takes place from
- rarer to denser medium
- denser to rarer medium
- normal to the surface separating the two media.
Numerical problems.
The speed of light in water is 2.25 × 108 ms–1. If the speed of light in vacuum is 3 × 108 ms–1, calculate the refractive index of water.
The refractive index of a transparent medium is always greater than ______.
If a beam of red light and a beam of violet light are incident at the same angle on the inclined surface of a prism from air medium and produce angles of refraction r and v respectively, which of the following is correct?
Noor, a young student, was trying to demonstrate some properties of light in her Science project work. She kept ‘X’ inside the box (as shown in the figure) and with the help of a laser pointer made light rays pass through the holes on one side of the box. She had a small butter-paper screen to see the spots of light being cast as they emerged.
Her friend noted the following observations from this demonstration:
- Glass is optically rarer than air.
- Air and glass allow light to pass through them with the same velocity.
- Air is optically rarer than glass.
- Speed of light through a denser medium is faster than that of a rarer medium.
- The ratio: sin of angle of incidence in the first medium to the ratio of sin of angle of refraction in the second medium, gives the refractive index of the second material with respect to the first one.
Which one of the combinations of the above statements given below is correct.
A pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same extent, if instead of water we use liquids like, kerosene or turpentine. Support your answer with reason.
When light passes from one medium to another the ray gets bent. This property of light is called ______.
A ray of light traveling in medium 1 strikes and travels into another transparent medium 2. If the speed of light is greater in medium 1, the ray will ______.
Light is refracted or bent while going from one medium to another because of its ______ changes.
How do twinkling stars occur? (or) what is the cause of the twinkling of stars?
A ray of light starting from diamond is incident on the interface separating diamond and water. Draw a labelled ray diagram to show. the refraction of light in this case.
When a ray of light travels normal to the given surface, then the angle of refraction is ______.
