Question

what do you understand by the resistivity of a substance
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Answer 1

Answer:

ANSWER IN THE ATTACHMENT ABOVE

Answer 2

Resistivity is the characteristic property of a substance which depends on the nature of the substance and its temperature. It is numerically equal to the resistance between the opposite faces of a 1 m cube of the substance.

l = 1m

r = d/2 = 0.2/2 mm = 0.1 mm = 0.0001m,

R = 10 ohm

We know that,

R = p.1/A

P = RA/I

= (10 × π × (0.0001)2)/1

= 31.4 × 10-8 Ω m