Question

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$\red\rightarrow$What is meant by the electrical resistivity of a material? Derive its S.I. unit. Describe an experiment to study the factor on which the resistance of a conducting wire depends.

Answer 1

Answer:

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If I is the length of the conductor, A its area of the crosssection and R its total resistance then, Where P is a constant of proportionality and is called the electrical resistivity of the material of the conductor. The SI unit of resistivity is Ohm meter.

Answer 2

Explanation:

Resistivity, electrical resistance of a conductor of unit cross-sectional area and unit length. A characteristic property of each material, resistivity is useful in comparing various materials on the basis of their ability to conduct electric currents. High resistivity designates poor conductors.

The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m).

Experiment to study the factors on which the resistance of conducting wire depends.

1) Take a nichrome wire, a torch bulb, a 10 W bulb and an ammeter (0 – 5 A range), a plug key and some connecting wires.

2) Set up the circuit by connecting four dry cells of 1.5 V each in series with the ammeter leaving a gap XY in the circuit, as shown in Fig.

3) Observation: It is observed that resistance depend on material of conductor. Length of conductor determines resistance Resistance depends on area of cross section.