Question

A copper wire has a diameter of 0.5 mm and resistivity of 1.6 *10^8 ohm metre
1) what will be the length of the wire to make the resistance 12 ohm
2) how much will be the resistance of another copper wire of same length but the half of diameter​

Answer 1

Answer:

122.72 m

Explanation:

Given :

Resistivity ρ = 1.6 × 10⁻⁸ Ω m

Resistance R = 10 Ω

Diameter d = 0.5 mm

= > Radius r = 0.25 mm = 0.25 × 10⁻³ m = 2.5 × 10⁻⁴ m

= > Area A = 6.25 π × 10⁻⁸ m²

We are asked to find length L :

We know :

R = ρ ( L ) / ( A )

= > L = ( R × A ) / ρ

Putting values here we get :

= > L = ( 10 × 6.25 π × 10⁻⁸ ) / 1.6 × 10⁻⁸ m

= > L = 62.5 π / 1.6

= > L = 122.72 m

Hence we get required answer!

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