Advertisements
Advertisements
Question
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?
Advertisements
Solution
Length of the cable wire, l = 2 m
Area of cross-section, A = 1.55 × 10−6 m2
APPEARS IN
RELATED QUESTIONS
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.
Which of the following are conductors and which are insulators?
Sulphur, Silver, Copper, Cotton, Aluminium, Air, Nichrome, Graphite, Paper, porcelain, Mercury, Mica, Bakelite, Polythene, Manganin.
What is the general name of the substances having infinitely high electrical resistance?
Which has less electrical resistance : a thin wire or a thick wire (of the same length and same material)?
Name the electrical property of a material whose symbol is "omega".
What happens to the resistance as the conductor is made thicker?
Which has more resistance:
a thick piece of nichrome wire or a thin piece?
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?
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?
The element used almost exclusively for filaments of incandescent lamps:
Assertion: Conductors allow the current to flow through themselves.
Reason: They have free charge carriers.
Plastic insulation surrounds a wire having diameter d and length l as shown above. A decrease in the resistance of the wire would be produced by an increase in the ______.
How will the resistance of a wire be affected if its
- length is doubled, and
- radius is also doubled ?
Give justification for your answer.
