Question

A wire is stretched to 3 times it's original length. Find its new resistance and resistivity?

Answer 1

To solve the problem mentioned in the question,we have to apply the Ohm's law of electricial resistance.

According to the Ohm's law,the relationship between the wire length and electricial resistance is;

resistance = resistivity × length / area

Let the

Resistivity=R

Initial length= l

Area = a

Now for the final stage

Resistivity= R

Final length= 3l

Area = a

So the initial resistance= Rl/a

Final resistance= R×3l/a = 3(Rl/a)

So if the wire length increases 3 times,the resistance also increases 3 times.

Answer 2

Answer:

Resistance will increase 9 times and resistivity will remain same for same material.

Step-by-step explanation:

According to ohm's law,R=rho×l/A =rho(l×l)/(A×l)

1. Now in first case we have,R=rhol^2/Volume
2. Now in scond case,R'=rho×(3l)^2/volume

therefore,R'/R=(rho×9l^2/volume)/(rho×l^2/volume)

=9

Hence the new resistance become 9 times from original resistance.

And resistivity will remain same.