Question

Find the resistance of the wire if: L=20π mm, rho=100Ωm and d=4mm?

Answer 1

Given,

• l = 20π

• ρ = 100Ω

• d = 4 mm

• r = 2 mm

We know,

R = ρl/A

⇒R = 100*20π/πr²

⇒R = 2000π/π*2²

⇒R = 2000/4

⇒R = 500Ω

Answer 2

Answer:

 5 × 10⁵ Ω

Explanation:

Given :

Length L = 20 π mm = 20 π × 10⁻³ m

Diameter d = 4 mm = 4 × 10⁻³ m

= > Radius r = 2 × 10⁻³ m

= > Area A = 4 π × 10⁻⁶ m²

Resistivity ρ = 100 Ω m

We are asked to find resistance :

We know :

R = ρ ( L ) / ( A )

Putting values here we get :

= > R = 100 ( 20 π × 10⁻³  ) / ( 4 π × 10⁻⁶  ) Ω

= > R = 100 ( 5 × 10⁻³  ) / ( 10⁻⁶  ) Ω

= > R = 100 ( 5 × 10³  )  Ω

= > R = 5 × 10⁵ Ω

Hence we get required answer!