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प्रश्न
Describe the principle of simple periscope through an outline ray diagram. Give one of its uses.
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उत्तर
Simple periscope is based upon the principle of reflection. It consists of cardboard or wooden tube, bent twice at right angles, and is provided with two openings as shown in the figure. Two plane mirrors are fixed at the bends of the tube at an angle 45° to the framework, such that the mirrors face each other. The tube is completely blackened from inside to avoid any reflection from its sides.
The parallel rays coming from an object at a higher plane, strike the plane mirror at an angle of 45° and hence are reflected through an angle of 45°.
These reflected rays strike the second mirror at an angle of 45° and hence are further reflected through an angle of 45°. These reflected rays on reaching the eye from the image on retina.
Use of periscope: It is used by soldiers in trench warfare.
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संबंधित प्रश्न
State the characteristics of the image formed by a plane mirror.
Select the correct alternative
The property due to which a light ray striking a surface is returned back into the same medium is called
The diagram below in figure shows an object XY in front of a plane mirror MM1 . Draw on the diagram, path of two rays from each point X and Y of the object to show the formation of its image .
Copy the figure. By taking two rays from point A, show the formation of image. State four characteristics of the image.
Give two uses of concave mirror.
What is a real image?
Match the following:
| 1. | Rubber | a. | Erect |
| 2. | Greased paper | b. | Inverted |
| 3. | Real image | c. | Opaque medium |
| 4. | Virtual image | d. | Translucent medium |
Play with a mirror
Write your name with a sketch pen on a thin sheet of paper, polythene or glass. Read your name on the sheet while standing in front of a plane mirror. Now look at your image in the mirror.
A burning candle in water
Take a shoe box, open on one side. Place a small lighted candle in it. Place a clear glass sheet (roughly 25 cm × 25 cm) in front of this candle figure. Try to locate the image of the candle behind the glass sheet. Place a glass of water at its position. Ask your friends to look at the image of the candle through the sheet of glass. Ensure that candle is not visible to your friends. Your friends will be surprised to see the candle burning in water. Try to explain the reason.
