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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. - Science

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प्रश्न

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.

संख्यात्मक
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उत्तर

Given: Speed of light in water (υ) = 2.25 × 108ms– 1
Speed of light in vacuum (c) = 3 × 108ms– 1
Solution:
μ = `"c"/"υ"` ⇒ μ =`(3×10^8"ms"^(−1))/(2.25×10^8"ms"^(−1))`
∴ μ = 1.33

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अध्याय 6: Light - Exercise [पृष्ठ ७८]

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सामाचीर कलवी Science [English] Class 9 TN Board
अध्याय 6 Light
Exercise | Q IX. 3. | पृष्ठ ७८

संबंधित प्रश्न

A ray of light travelling in air is incident on a rectangular glass block and emerges out into the air from the opposite face. Draw a labelled ray diagram to show the completer path of this ray of light. Mark the two points where the refraction of light takes place. What can you say about the final direction of ray of light?


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.


When a ray of light travelling in glass enters into water obliquely:

(a) it is refracted towards the normal
(b) it is not refracted at all
(c) it goes along the normal
(d) it is refracted away from the normal


Define the principal focus of a concave mirror.


Choose the correct option from given alternative:
A real image is formed by the light rays after reflection or refraction when they:
(A) actually meet or intersect with each other.
(B) actually converge at a point
(C) appear to meet when they are produced in the backward direction.
(D) appear to diverge from a point.
Which of the above statements are correct?


Identify the wrong figure from the following.


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:

  1. Glass is optically rarer than air.
  2. Air and glass allow light to pass through them with the same velocity.
  3. Air is optically rarer than glass.
  4. Speed of light through a denser medium is faster than that of a rarer medium.
  5. 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 surface will not reflect most of the light falling on them?


Light bends as it passes from one medium to another. What is this phenomenon called?


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.


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