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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
| 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 |
What type of reflection of light takes place from a cinema screen?
What is meant by 'reflection of light'?
The angle of reflection is equal to the angle of incidence:
(a) always
(b) sometimes
(c) under special conditions
(d) never
Image is formed by a mirror due to refraction of light.
When a ray of light travels from water to air, it bends ............. the normal.
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 angle of incidence for a ray of light having zero reflection angle is ______.
How does the light travel?
The ratio of the sine of the angle of incidence to the sine of ______ is constant.
