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प्रश्न
Explain the working of a periscope.
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उत्तर
Periscope:
- It is an instrument used for viewing bodies or ships, which are over and around another body or a submarine.
- It is based on the principle of the law of reflection of light.
- It consists of a long outer case and inside this case mirrors or prisms are kept at each end, inclined at an angle of 45°.
- Light coming from the distant body falls on the mirror at the top end of the periscope and gets reflected vertically downward.
- This light is reflected again by the second mirror kept at the bottom, so as to travel horizontally and reach the eye of the observer.
- In some complex periscopes, optic fiber is used instead of mirrors for obtaining a higher resolution.
- The distance between the mirrors also varies depending on the purpose of using
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संबंधित प्रश्न
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.
State and explain the laws of reflection of light at a plane surface (like a plane mirror), With the help of a labelled ray-diagram. Mark the angles of 'incidence' and 'reflection' clearly on the diagram. If the angle of reflection is 47.5°, what will be the angle of incidence?
The image in a plane mirror is virtual and laterally inverted. What does this statement mean?
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.
A small air bubble in a glass block when seen from above appears to be raised because of ______.
Explain how the formation of a rainbow occurs.
The speed of light varies in different media.
The refractive index of a transparent medium is always greater than ______.
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.
How does the light travel?
