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प्रश्न
Why do telephone wires sag in summer ?
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उत्तर
The telephone wires will sag in summer due to expansions and will break in winter due to contraction.
Therefore, while putting up the wires between the poles, care is taken that in summer they are kept slightly loose so that they may not break in winter due to contraction.
While in winter they are kept light so that they may not sag too much in summer due to expansion.
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संबंधित प्रश्न
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_________ determines the degree of hotness or coldness of a body.
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Metals are _______ of heat.
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Name two substances which expand on heating.
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Select good and bad conductors of heat from the following:
copper, mercury, wood, iron, air, saw-dust, cardboard, silver, plastic, wool.
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When we heat them the force of attraction between the molecules decreases and the ice cubes become ______.
Match the following
| 1. | Solid to liquid | a. | Condensation |
| 2. | Liquid to gas | b. | Deposition |
| 3. | Gas to solid | c. | Melting |
| 4. | Gas to liquid | d. | Vaporization |
______ is greater for liquids than solids and it is maximum in gases.
