Define 1 ohm resistance.
A student has a resistance wire of 1 ohm. If the length of this wire is 50 cm, to what
length he should stretch it uniformly so as to obtain a wire of ` 4 Omega` resistance? Justify
your answer .

Explanation

1 ohm is the resistance of a conductor such that when a potential difference of 1 volt
is applied to its ends, a current of ampere flows through it.
Resistance, 1R_(1) = 1 Omega, L_(1) 50 cm = (50)/(100) m = (1)/(2)`m
` Required resistance, `R_(2) = 4 Omega`
Required length, `L_(2) = ?`
R `propto` L
`(R_(1))/(L_(1)) ` Constant, `(R_(2))/(L_(2))` = Constant
`(R_(1))/(L_(1)) = (R_(2))/(L_(2)) = (1)/(1//2) = (4)/(L_(2)) rArr (1xx 2)/(1) = (4)/(L_(2))`
`L_(2) = (4)/(2) therefore L_(2) = 2n`