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प्रश्न
On what factors does the resistance of a conductor depend?
List the factors on which the resistance of a uniform cylindrical conductor of a given material depends.
List two factors on which the resistance of a rectangular conductor depends.
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उत्तर
Factors on which the resistance of a conductor depends:
- Length of conductor: Resistance is directly proportional to the length of the conductor. This means Resistance increases with an increase in the length of the conductor. This is the cause that long electric wires create more resistance to the electric current.
- Area of cross-section: Resistance is inversely proportional to the area of the cross-section of the conductor. This means Resistance will decrease with an increase in the area of the conductor and vice versa. This is the cause that thick copper wire creates less resistance to the electric current.
- Temperature: Resistance is directly proportional to the temperature.
- Nature of material: Some materials create the least hindrance and hence are called good conductors. Silver is the best conductor of electricity. While some other materials create more hindrance in the flow of electric current, i.e. flow of electrons through them. Such materials are called bad conductors. Bad conductors are also known as insulators. The hard plastic is one of the best insulators of electricity.
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संबंधित प्रश्न
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 copper and aluminium wires usually employed for electricity transmission?
Why are alloys commonly used in electrical heating devices? Give reason.
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)?
Classify the following into good conductors, resistors and insulators:
Rubber, Mercury, Nichrome, Polythene, Aluminium, Wood, Manganin, Bakelite, Iron, Paper, Thermocol, Metal coin
What is meant by the "resistance of a conductor" ? Write the relation between resistance, potential difference and current.
What happens to the resistance as the conductor is made thinner?
Which among iron and mercury is a better conductor of electricity?
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.
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.
Materials which allow larger currents to flow through them are called:
Assertion: Conductors allow the current to flow through themselves.
Reason: They have free charge carriers.
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.
