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प्रश्न
How does the resistance of a wire change when:
its material is changed to one whose resistivity is three times?
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उत्तर
Resistance,
`R=l/A`
where l = length of wire
A= area of cross-section of the wire
When the material is changed to one whose resistivity is three times:
`R=(3rho)/A=3R`
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संबंधित प्रश्न
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a thick piece of nichrome wire or a thin piece?
Give two examples of substances which are good conductors of electricity. Why do you think they are good conductors of electricity?
Calculate the resistance of a copper wire 1.0 km long and 0.50 mm diameter if the resistivity of copper is 1.7 × 10−8 Ω m.
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area of cross-section of the conductor?
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What would be the effect on the resistance of a metal wire of:
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Use the data in the Table given below to answer the following –
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Table give below Electrical resistivity of some substances at 20°C
| Electrical resistivity of some substances at 20°C | ||
| − | Material | Resistivity (Ω m) |
| Conductors |
Silver | 1.60 × 10−8 |
| Copper | 1.62 × 10−8 | |
| Aluminium | 2.63 × 10−8 | |
| Tungsten | 5.20 × 10−8 | |
| Nickel | 6.84 × 10−8 | |
| Iron | 10.0 × 10−8 | |
| Chromium | 12.9 × 10−8 | |
| Mercury | 94.0 × 10−8 | |
| Manganese | 1.84 × 10−6 | |
| Alloys |
Constantan (alloy of Cu and Ni) |
49 × 10−6 |
| Manganin (alloy of Cu, Mn and Ni) |
44 × 10−6 | |
| Nichrome (alloy of Ni, Cr, Mn and Fe) |
100 × 10−6 | |
| Insulators | Glass | 1010 − 1014 |
| Hard rubber | 1013 − 1016 | |
| Ebonite | 1015 − 1017 | |
| Diamond | 1012 − 1013 | |
| Paper (dry) | 1012 | |
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