Question

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

Answer 1

net resistance is nothing but equivalent resistance
equalent resistance =

1/Req = 1/1+1/+1/1+1/1

=
therefore net resistance is 4.

Answer 2

Answer:

R=4 ohm

Explanation:

R=4 ohm

R=ρ l/A

The wire is cut into four equal pieces

resistance of each wire

=4/4ohm

=1ohm

Each piece is then stretched to length ‘l’ ie 4 times the previous  

Therefore area becomes ¼

new resistance= ρ l./A.=16 ohm

the four wires are joined in parallel.

Total new resistance

1/R_tot=1/16+1/16+1/16+1/16

R_tot=4 ohm