Question

the specific resistance of the material of wire is 3×10⁷ ohm m. if the resistance of the wire is 4 ohm and radius of the wire is 0.6mm calculate the length of the wire​

Answer 1

Answer: The length of the wire is 15m

Explanation:

Given : specific resistance ( ρ ) = 3 × 10⁷ ohm m

Resistance of wire ( R ) = 4 ohm

Radius of wire ( r ) = 0.6 mm = 0.0006 m

To find : length of the wire ( l )

Formula : R = ρ × l / A

Where A = Area of wire .

∴ A = πr²

∴ A = 3.14 × ( 0.0006 )²

∴ A = 3.14 × 3.6 × 10⁷

∴ A = 11.3 × 10⁷

Substituting all the values in the formula,

∴ 4 = 3 × 10⁷ × l / 11.3 × 10⁷

∴ 4 = 3 × l / 11.3

∴ l = 4 × 11.3 / 3

∴ l = 15 m