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प्रश्न
Give two examples of substances which are good conductors of electricity. Why do you think they are good conductors of electricity?
उत्तर
Copper and aluminium are good conductors of electricity because their resistivity is very low.
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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 happens to the resistance as the conductor is made thinner?
What happens to the resistance as the conductor is made thicker?
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?
How does the resistance of a conductor depend on:
area of cross-section of the conductor?
Write the relation between resistance and electrical resistivity of the material of a conductor in the shape of a cylinder of length `'l'` and area of cross-section `'A'` . Hence derive the S.I. unit of electrical resistivity.
How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistors R1, R2 and R3 in series connected to a battery of V volts?
The effective resistance between A and B is:
