Define restivity with SI system of units. Derive an expression for resistivity in terms of resistance of wire.
Answers
Answer:
Resistivity , ρ=
l
R×A
where, R is the resistance of the conductor
A is the area of cross - section of the conductor
l is the length of the conductor.
(b) Ohm - meter
(c)
1. Resistance is the property of the conductor , while resistivity is the property of the material of the conductor.
2. Resistance of a conductor is the opposition to the flow of electric current through it. Resistivity of a substance is the opposition to the flow of electric current by a rod of that substance which is 1 m long and 1m
2
in cross section.
3. Resistance of a conductor depends on length, thickness , nature of material and temperature of the conductor ; while resistivity of a substance depends on the nature of the substance and temperature.
(d) Resistivity of a substance depends on the nature of the substance and its temperature. It does not depend on the length or thickness of the conductor.
(e) l=1m
R=26ohm
r=
2
d
=
2
0.3
mm=0.15mm=0.15×10
−3
m
ρ=
l
R×A
=
l
R×πr
2
=
1
26×3.14×(0.15×10
−3
)
2
=1.83×10
−6
Ωm
Answer:
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