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What is electrical resistivity ? In a se...

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

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Electrical resistivity is defined as the resistance of a conductor of length 1 m and area of cross section 1 m sq. When the length of the wire is doubled, its resistance also doubles (increases), a resistance is directly proportional to length of the wire. `R prop l` when its resistance increase its current decrease as resistance is inversely proportional to current
`R prop (1)/(I)`
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