Question

A 6 ohm Resistance wire is doubled up by folding. Calculate the New resistance of the wire.

Answer 1

resistance is given as

R = ρl/A

 

where 

ρ is the resistivity (stays constant)

l is the length

A is the cross-sectional area

 

now initially R = 6 ohms

 

but if we fold the wire on itself then

A' = 2A

l' = l/2

 

so, new resistance

R' = ρl'/A' = ρl/2/2A

or

R' = R/4

 

so, the new resistance will be R' = 6/4 ohms