Question

the resistivity of 3 material given as :
Sample A B
Resistivity 1.6x10^-8 7.5x10^17
(ohm-m) C
> 44x10^-6
a. which of them is a good conductor and which is an insulator. Give reason
b. 'A' resistance wire (4ohm) is doubled. Calculate the new resistance of the wire

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Answer 1

Explanation:

Resistivity is the property of the material that how much it will offer resistance to the flow of electrons.

Resistance is directly proportional to resistivity and hence more resistivity would mean more resistance,

Now considering the resistivity’s of A,B and C, we find that the resistivity of B is the most, hence B is an insulator

Also the resistivity of A is least, hence it would be a good conductor

B) Now if A has resistance of 4 ohm and it is doubled, then its new resistance would be 8 ohm

Answer 2

Answer:

(a) Resistivity is very low for conductors and high for insulators. So sample A is a good conductor and sample B is a good insulator.  

(b) R = ρl/A

    If length is doubled resistance is also doubled if A is constant. So the new resistance is 8 Ω.

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