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प्रश्न
What is refraction of light?
What is refraction of light? Explain with the help of an example.
Explain the refraction of light.
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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 |
State the uses of plane mirrors.
What is meant by 'reflection of light'?
Define the following terms used in the study of reflection of light by drawing a labelled ray-diagram:
- Incident ray
- Point of incidence
- Normal
- Reflected ray
- Angle of incidence
- Angle of reflection
The angle of reflection is equal to the angle of incidence:
(a) always
(b) sometimes
(c) under special conditions
(d) never
A ray of light passes from air into a block of glass. Does it bend towards the normal or away from it?
As light rays pass from water into glass, are they refracted towards the normal or away from the normal?
Fill in the following blank with suitable word:
Light travelling along a normal is ...............refracted.
Fill in the following blank with suitable word:
Light bends when is passes from water into air. We say that it is ............
Light travels more quickly through water than through glass.
If a ray of light passes from glass into water, which way will it bend : towards the normal or away from the normal?
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.
With the help of a labelled diagram, explain why a tank full of water appears less deep than it actually is.
- With the help of a diagram, show how when light falls obliquely on the side of a rectangular glass slab, the emergent ray is parallel to the incident ray.
- Show the lateral displacement of the ray on the diagram.
How does the light have to enter the glass:
for no refraction to happen?
The speed of light is more in glass than in water.
The depth of a pond when seen from above appears to be less.
Light travels at a lower speed in water than in air.
Water is optically .......... than air.
Draw a diagram showing the refraction of a light ray from water to glass. Label on it the incident ray, the angle of incidence (/), and the angle of refraction (r)
What is the cause of refraction of light when it passes from one medium to another?
A ray of light A incident from air suffers partial reflection and refraction at the boundary of water.
- Complete the diagram showing (i) the reflected ray B and (ii) the refracted ray C.
- How are the angles of incidence i and refraction r related?
Define the principal focus of a concave mirror.
The laws of reflection hold true for ______.
Light changes its direction when going from one transparent medium to another transparent medium. This is called _______.
Identify the wrong figure from the following.
Write scientific reason.
The bottom of a pond appears raised.
Write a 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.
Write scientific reason.
A pencil appears to be broken near the surface of water.
Observe the given figure and write appropriate phenomenon of light in the box.
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.
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.
Which object use the reflection of light?
The bending of light as it passes from one medium to another 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 ______.
The ratio of the sine of the angle of incidence to the sine of ______ is constant.
Why a pencil partly immersed in water appears to be bent at the water surface.
Match the following:
| Column I | Column II | ||
| 1. | r > 90 | a. | Light gazes at the surface of separation between the two modes. |
| 2. | r = 90 | b. | No refraction. |
| 3. | r < 90 | c. | Refracted ray away from the normal |
The part of light that enters into the other medium and travels in a straight path but in a direction different from its initial direction is called:
The ray that enters the second medium after crossing the boundary is called the:
The constant \[\frac{\sin i}{\sin r}\] for a given pair of media is called the:
Which of the following relations is called Snell's Law?
A medium with a higher refractive index is:
