What is meant by resistance of conductor? Name and define its Sl unit. List the factors by which the resistance of a wire is affected. What happens if
i] its length is doubled
ii] its radius is doubled?

Explanation

Resistance is the property of the conductor to resist the flow of current.
Sl unit of Resistance is Ohm.
Resistance of a conductor directly depends upon Length of the wire L
Inversely depends upon Area of Cross section of the conductor I/A
Nature of material used.
Therefore, `R=(rhoL)/A`
Length of the conductor is double, means you are stretching that given length to double it. As a result, the wire becomes thin due to stretching. So its area of cross section will be halved [since the volume remains constant].
So new resistance
`R_(N)=(rho2L)/(A/2)=(4rhoL)/A=4R`
Hence the new resistance will increase will become one-fourth.