Question

A piece of copper of mass 50g is drawn into a wire of length 50m. find the resistance of the wire .the density and the specific resistance of copper are 8.9×x10^4 kg/m^3 and 1.7×10^-8 ohm m respectively

Answer 1

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Answer 2

Answer:

Resistance of the wire is 75.65 ohms

Explanation:

It is given that,

Mass of the copper piece, m = 50 g = 0.05 kg

Length of wire, l = 50 m

Density of copper wire, $d=8.9\times 10^4\ kg/m^3$

Specific resistance, $\rho=1.7\times 10^{-8}\ \Omega-m$  

Resistance, $R=\rho\dfrac{l}{A}$.......(1)

Density, $d=\dfrac{m}{V}=\dfrac{m}{A.l}$

$A=\dfrac{m}{dl}$

Put the value of A in equation (1). So,

$R=\rho\dfrac{l^2d}{m}$

$R=1.7\times 10^{-8}\times \dfrac{50^2\times 8.9\times 10^4}{0.05}$

R = 75.65 ohms

Hence, the resistance of the wire is 75.65 ohms