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Q19. a) Give one example to show how the resistance depends on the nature of material of the conductor b) Calculate the resistance of an aluminum cable of length 10km and diameter 2.0mm if the resistivity of aluminum is 2.7×10-8Ωm.
Q19. a) Give one example to show how the resistance depends on the nature of material of the conductor b) Calculate the resistance of an aluminum cable of length 10km and diameter 2.0mm if the resistivity of aluminum is 2.7×10-8Ωm.
CBSE | Class 10 | Electricity | Lakhmir Singh | Physics
Q19. a) Give one example to show how the resistance depends on the nature of material of the conductor b) Calculate the resistance of an aluminum cable of length 10km and diameter 2.0mm if the resistivity of aluminum is 2.7×10-8Ωm.

Answer:

a)  Let us consider two wires with same length and diameter. Let these two wires be of copper metal and nichrome alloy. We know that the resistance of nichrome wire is 60 times more than that of the copper wire. Therefore, it is understood that the resistance depends on the nature of the material used in the conductor.

b) Given in question :

l = 10km = 10000m , d = 2mm, r = 1mm = 10-3m

ρ = 2.7×10-8Ωm

We know that, R = ρl/A

Substituting the values we get,

R = 86Ω

i

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