Question

If 'R' be the resistance of a uniform wire of length 'l'and area 'A'. Then the resistance of the wire of same material of length '2l' and area '2A' will be a)R b)2R c)R/4 d)R/2 ​

Answer 1

Answer:

a)R

R=ρ(L/A)

R'=ρ(L'/A') where L'=2L

A'=2A

R'=ρ(2L/2A)=R

Answer 2

Given,

'R' be the resistance of a uniform wire of length 'l' , and area 'A'.

To find,

The resistance of the wire of the same material of length '2l' and area '2A'.

Solution,

• Resistance of material is directly proportional to the length of the conductor and inversely proportional to the area of cross-section.

      R = р(l/A), where R is the resistance and l is the length of the conductor, a is the area of cross-section and р is resistivity constant.

Now, length = 2l

area = 2A

R2 = р(2l/2A)

R2 =  р(l/A).

Hence,  the resistance of the wire of same material of length '2l' and area '2A' will be R. Option (a)