Question

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What is electrical resistivity? In series electrical circuit comprising a resistor made up of metallic wire,the ammeter reads 5 Ampere. The reading of the ammeter decrease to half when the length of the wire is doubled. Why?

Answer 1

Hello Dear 

Resistivity is the measure of material's ability to oppose the flow of current 

Resistivity of a conductor is a property of a material of a conductor . Unit of resistivity is Ohm meter , Ω m 

Resistivity of the material of a conductor changes with temperature . 

R = ρ l / A 

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As (R) resistance is directly proportional to the length of conductor , when length is increased .. resistance increase and current decreases . Hence the reading of ammeter decreases when length is increased . 

Answer 2

Answer:

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Explanation:

Ans. The inherent property of a conductor because of which it resists the flow of electric current is called resistivity. Resistivity for a particular material is unique

Resistance varies directly as length of the conductor.

Current varies inversely as resistance.

So, when length of the wire is doubled, its resistance becomes double. When resistance becomes double, current becomes half.

This explains why the reading of ammeter decreases to half when the length of the wire is doubled.