Question

A copper wire has cross sectional area 4* 10^-6 m^2 and resistivity of 1.6 *10^-8 ohm m calculate the length of the wire to make it resistance 10 ohm . by how much does the resistance change if the diameter is doubled .​

Answer 1

Length of the wire is 2500 m

Explanation:

Given that,

Area of cross section, $A=4\times 10^{-6}\ m^2$

Resistivity of the copper wire, $\rho=1.6\times 10^{-8}\ \Omega -m$

Resistance, R = 10 ohms

The resistance of the wire is given by :

$R=\rho \dfrac{l}{A}$

l is length of the wire

$l=\dfrac{RA}{\rho}\\\\l=\dfrac{10\times 4\times 10^{-6}}{1.6\times 10^{-8}}\\\\l=2500\ m$

If the diameter of the wire is doubled, the resistance will decreased by one fourth. So, new resistance becomes 2.5 ohms.

Learn more,

Resistivity

https://brainly.in/question/14836079