Question

A wire of length 10cm has a resistance of 4 ohm. If the wire is
stretched to double its length. Find the New Resistance ?​

Answer 1

Answer:

8 OHMS

Explanation:

Let area of cross section be A 1

L¹ = 10 cm and it is stretched and doubled then l ² = (10×2=20cm) . And resistance is 2 ohms (given part of question)

If it is stretched to double then new area will become A²=A¹/2 that is half of earlier.

Material is same , so resistivity will remain same so no need to put resistivity in the formula

Resistance1 = Length1 / Area1

=> 2 = L1/A1

=>2=10/A1

=>2A1=10

=>A1=5 cm ²

Resistance 2= length2/area2

R2=20/a1/2

R2=20/5/2

r2=20/2.5

R2= 8 Ohmns