Advertisements
Advertisements
प्रश्न
Give two examples of substances which are good conductors of electricity. Why do you think they are good conductors of electricity?
Advertisements
उत्तर
Copper and aluminium are good conductors of electricity because their resistivity is very low.
APPEARS IN
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 | |
What is (a) the highest, (b) the lowest total resistance that can be secured by combinations of four coils of resistance 4 Ω, 8 Ω, 12 Ω, 24 Ω?
A copper wire has diameter 0.5 mm and resistivity of 1.6 × 10−8Ω m. What will be the length of this wire to make its resistance 10 Ω? How much does the resistance change if the diameter is doubled?
Why are alloys commonly used in electrical heating devices? Give reason.
What is meant by conductors and insulators? Give two examples of conductors and two of insulators.
Classify the following into good conductors, resistors and insulators:
Rubber, Mercury, Nichrome, Polythene, Aluminium, Wood, Manganin, Bakelite, Iron, Paper, Thermocol, Metal coin
What happens to the resistance as the conductor is made thinner?
Name the electrical property of a material whose symbol is "omega".
Which among iron and mercury is a better conductor of electricity?
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?
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.
What would be the effect on the resistance of a metal wire of:
increasing its diameter?
How does the resistance of a wire change when:
its material is changed to one whose resistivity is three times?
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 resistance of a wire of 0.01 cm radius is 10 Ω. If the resistivity of the wire is 50 × 10-8 Ω, find the length of this wire.
How will the resistance of a wire be affected if its
- length is doubled, and
- radius is also doubled ?
Give justification for your answer.
