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​

Answer 1

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.

Answer 2

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