Question

The resistivity of two material A and B are in the ratio of 2 is to 3 if the diameter of a is taken what should be the length of the such that the resistance of A and B are equal

Answer 1

The formula for the resistivity(ρ) depending upon the resistance(R), lenght(l), and area(a).

• The resistivity ρ=Ra/l
• As the ratio of two material is ρ₁/ρ₂=2/3
• Area is same as the diameter of both are same
• Length are changed l₁ and l₂
• Let resistance is different in both cases R₁ and R₂.
• 2/3=(R₁a/l₁) / (R₂a/l₂)
• 2/3=R₁l₂/R₂l₁
• That is for different resistance
• If the resistance is same then R₁=R₂=R
• Therfore 2/3=l₂/l₁