TODAY'S THIRD QUESTION
A wire of length 3 m and area of cross-section 1.7 × 10-6 m2 has a resistance 3 × 10-2 ohm.
a. What is the formula for resistivity of the wire and what is the unit of it
b. Calculate the resistivity of the wire
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Answers
Answer:
Correct Question:
A wire of length 3 m and area of cross-section 1.7 × 10⁻⁶ m² has a resistance 3 × 10⁻² Ωm
a. What is the formula for resistivity of the wire and what is the unit of it ?
b. Calculate the resistivity of the wire.
Solution:
a. Resistitvity formula and unit
Resistivity of the wire ρ = R × A / l
Where,
R = Resistance
l = length of the wire
A = Cross section of the wire
SI unit of Resistivity is Ωm.
b. Caluculate the resistivity of wire
Length of the wire ( l ) = 3 m
Area of the cross section ( A ) = 1.7 × 10⁻⁶ m²
Resistance ( R ) = 3 × 10⁻² Ω
We know that
Resistivity of the wire ( ρ ) = R × A / l
⇒ ρ = 3 × 10⁻² × 1.7 × 10⁻⁶ / 3
⇒ ρ = 1.7 × 10⁻⁸ Ωm
Therefore the Resistivity of the wire is 1.7 × 10⁻⁸ Ωm.
. Resistivity of the wire is given by
ρ=RA/L
And It unit is Ohm-m
b. In this case
L=3 m
A
=1.7×10^−6 m^2
R=3×10^−2 ohm
So
ρ=1.7×10^8 Ohm-m
