Question

7. A wire of length 100 cm, radius 0.15 mm has resistance of 6 12. Calculate the specific
resistance of the wire.
(Ans. 4.23 x 10-7-m​

Answer 1

Answer:

Hi there.

Given conditions ⇒

Length of the wire (l) = 120 cm.

Diameter of the cross section of the wire wire = 0.04 mm.

∴ Radius of the cross section of the wire(r) = 0.02 mm.

  = 0.002 cm.

Area of the cross-section of the wire = πr²

= 22/7 × (0.002)²

= 22/7 × 0.000004

= 12.57 × 10⁻⁶ cm²

Resistance of the wire (R) = 25 Ω

Using the Formula,

Specific Resistance (ρ) = Ra/l

∴ ρ = (25 × 12.57 × 10⁻⁶) ÷ 120

⇒ ρ = (314.25 × 10⁻⁶)/120

∴ ρ = 2.61875 × 10⁻⁶

∴ ρ = 2.62 × 10⁻⁶ Ω-cm.

Hence, the Specific Resistance of the Resistivity of the wire is 2.62 × 10⁻⁶ Ω-cm.

Hope it helps.