Question

A wire of resistence 'R' has length is doubled what will be its resistivity

Answer 1

Hi,

Here is your answer

Given:

Resistance of wire=R

To find:

New resistance R1 if length of wire is doubled

Solution:

We know that Resistance is given by the equation

R=ρl/A

From this equation we know that Resistance is directly proportional to length of coductor.

So if the length of the conductor doubles, Resistance is also doubled.

Therefore new resistance R1=2R

Notes:

1. Formula for resistance(R)

R=ρl/A where ρ is resistivity, l is length of conductor and A is area of cross section.

2. Resistance is directly proportional to length of conductor and inversely proportional to area of cross section.

Hope this helps you.

Answer 2

Answer:

Resistivity of the wire will remain the same

Explanation:

Let,

Resistance = R

Resistivity = ρ

Length = L

Area of cross-section = A

We know that,

R = ρL/A

Let,

New Resistance = R'

Resistivity = ρ

New Length = L' = 2L

New Area of cross-section = A'

When we double the length, the following may happen :

1. Area also may double so that, resistance remains constant
2. Resistance may double so that, area remains constant

In both the cases,

the resistivity always remains a constant

Resistivity is the property of the material and does not change with change in length or change in area

It can only be changed by changing the material that is, different materials have different resistivities

It can also be changed by changing the temperature