. Two wires are of same length and radius but one of them is copper and the other is of iron. Which will have more resistance? (Given the resistivity of copper = 1.62 x 10 -8 ohm meter and resistivity of iron = 10 x 10-8 ohm meter.)
Answers
We know that,
R = p l/A
Here; R is Resistance, p is rho (resistivity), l is length and A is Area of cross-section.
Also, p (rho) is constant. So,
R ∝ l/A
Resistance of a given wire is directly proportional to it's length and inversely proportional to it's area of cross-section.
Given that, resistivity of copper = 1.62 x 10^-8 ohm m and resistivity of iron = 10 x 10^-8 ohm m.
Also given that, two wires are of same length and radius but one of them is copper and the other is of iron.
As, the length and radius of wire are same. Radius is same, means the area of cross-section is same. Therefore, it depends upon the resistivity of wire.
(R = p l/A)
With increase in resistance, resistivity of the wire also increases and with decrease in resistance, resistivity decreases. The resistivity of iron wire is more.
Therefore, the resistance of iron wire is more.