Question

State Ohm’s law.

A metal wire of resistance 6Ω is stretched so that its length is increased lo twice the original length. Calculate Ike new resistance.

Answer 1

Ohm’s Law : It states, all physical conditions of a conductor remaining same, the current flowing through it is directly proportional to the potential difference at its ends. 

Let the original length be (l) and area of cross-section (a), such that its resistance is 6Ω Applying, R = K 1/a ⇒ 6 = kl/a …(i) 

When the length 2l, its area of cross-section becomes a/2. If R is the new resistance of conductor then : R = k 2 l/a/2 = 4 k l/a …..(ii) Dividing (ii) by (i) R/6 = 4R= 24Ω