Question

a wire has a uniform cross section of length L has a resistance of 4 ohm the wire is cut into 4 equal pieces each piece is then stretched to length L thereafter the four wires are joined in parallel calculate the net resistance

Answer 1

As wire has length of lcm and uniform resistance of 4

When it will be cutted in l/4 m 4 peaces
Then each piece would have resistance of 1ohm
Now as they are connected in parallel.

So 1/R effective = 1/4+1/4+1/4+1/4
=> 1
Hence resistance will be 1.
Hope you will like it.

Answer 2

Answer:

R=4 Ω (given)

R'=R/4 (∴l'=l/4)

=(ρ×l/a)/4

R (n)= {ρ×l*4/(a÷4)}/4

=4 ρ×l/a

=4×R Ω

=4×4 Ω

16 ohm

R(eq.) = (1/16+1/16+1/16+1/16)⁻¹

=(4/16)⁻¹

=4 ohm

Explanation:

Look,we know that the resistance of wire is 4Ω,

now if we cut the wire into 4 equal pieces then the new length is l/4,

so new resistance R'=R/4,

now we have to find another R,and trust me my readers,here is the real twist,the length is to be increased to l,but currently the length is l/4

so in order to make it l we will multiply the length by 4,again,we will divide the area by 4 as the rule suggest, and by calculation we will get R(n) is 16 Ω,

now simply calculate the equivalent resistance

done...thank me later