Question

the resistance of a wire of 0.01 cm radius is 10 ohms if the resistivity of the wire is 50 × 10^-8 ohm-metre find the length of the wire .

Answer 1

Given, Radius = 0.01 cm = 0.01 x 10-2m.

Resistivity p = 50 x 10-8Ωm.

Resistivity R = 10Ω



R=p*l/A=L/3.14*r²
=0.628m
Ans=0.628m

Answer 2

Radius=0.01×10^-2 metre ... I had converted it in metre

Resistivity=50×10^-8 ohm metre

Resistance=10 ohm

Now formula

Resistance=(resistivity×length)÷area of cross section of wire

Area of cross section of wire is,πr^2

Now put the values and u would get 0.628m as ur length...It's too simple...Hope u understand