A copper wire has a resistance of 0.5ohm. another copper wire is of the same mass as the first one but double its lenght. find the resistance of the second wiree.
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Mass of the copper wire is same.
M1 = M2
d*pi*r1^2*l1 = d*pi*r2^2*l2 (where d is the density of copper, r1 and r2 are the radius of 2 wires, l1 and l2 is their lengths)
Now, l2 = 2l1
Hence, d*pi*r1^2*l1 = d*pi*r2^2*2l1
r1^2 = 2r2^2
r2^2 = r1^2/2
For first wire, Resistance = rho*l1/A1
0.5 = rho*l1/pi*r1^2
For second wire, resistance = rho*l2/A2
= rho*l2/pi*r2^2
= rho*2l1/pi(r1^2/2)
= 4( rho*l1/pi*r1^2 )
= 4*0.5
= 2 ohmif u like it please mark as branliest
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