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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.
संबंधित प्रश्न
Use the data in the Table given below to answer the following –
Which among iron and mercury is a better 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 | |
Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:
Fill in the following blanks with suitable words:
Copper is a good .......... Plastic is an ..........
What is meant by conductors and insulators? Give two examples of conductors and two of insulators.
Which has less electrical resistance : a thin wire or a thick wire (of the same length and same material)?
Which has more resistance:
a long piece of nichrome wire or a short one?
What do you understand by the "resistivity" of a substance?
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?
What will be the resistance of a metal wire of length 2 metres and area of cross-section 1.55 × 10−6 m2 if the resistivity of the metal be 2.8 × 10−8 Ω m?
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.
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?
What would be the effect on the resistance of a metal wire of:
increasing its length?
The figure blow shows a variable resistor in a dimmer switch.
How would you turn the switch to make the lights: (a) brighter, and (b) dimmer? Explain your answer.
Materials which allow larger currents to flow through them are called:
The element used almost exclusively for filaments of incandescent lamps:
The effective resistance between A and B is:
How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistances in series connected to a battery?
