Question

Calculate the length of wire of resistance of 10ohm and area of cross section 0.5 cm in S.I. units. The specific resistance of wire is 0.0008 ohm-cm ​

Answer 1

Given :

→ Resistance of the wire (R) = 10Ω

→ Area of cross section of the wire (A) = 0.5 cm

→ Resistivity (ρ) = Specific resistance = 0.0008 Ω - cm

To find :

Length of the wire

Solution :

As we know that

★ ρ = R × A/l ★

→ ρ × l = R × A

→ l = R × A/ρ

Where,

ρ(rho) = Resistivity

R = Resistance

A = Area of cross section

l = Length of the wire

According to the question

Convert "cm" into "m"

Focus Zone : = 1 m = 100 cm

→ Area of cross section of the wire = 0.5 cm

→ A = 0.5/100 = 0.005 m

→Resistivity = Specific resistance =0.0008 Ω - cm

→ ρ = 0.0008/100 = 0.000008 Ω - m

Now,

→ l = R × A/ρ

→ l = 10 × 0.005/0.000008

→ l = 10 × 5/8 × 1000000/1000

→ l = 10 × 5/8 × 1000

→ l = 10 × 5 × 125

→ l = 50 × 125

→ l = 6250 m

•°• Length of the wire is 6250 m

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