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प्रश्न
Why are copper and aluminium wires usually employed for electricity transmission?
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उत्तर
Copper and aluminium wires are often used to transmit electricity because:
- Copper and aluminium are good conductors of electricity also have low resistivity.
- Copper and aluminium have a low resistance, which makes them good conductors of electricity.
- Wires can be made easily from these.
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संबंधित प्रश्न
On what factors does the resistance of a conductor depend?
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A wire is 1.0 m long, 0.2 mm in diameter and has a resistance of 10 Ω. Calculate the resistivity of its material?
Give two examples of substances which are good conductors of electricity. Why do you think they are good conductors of electricity?
How does the resistance of a conductor depend on:
area of cross-section of the conductor?
How does the resistance of a conductor depend on:
temperature of the conductor?
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increasing its length?
The figure blow shows a variable resistor in a dimmer switch.

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The element used almost exclusively for filaments of incandescent lamps:
The effective resistance between A and B is:

Use the data in the Table given below to answer the following –
Which material is the best conductor?
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 | |
