A copper wire of conductance 72 Ω-1 is melted and redrawn to thrice its original length. Find the Conductance of stretched wire.
6 Ω-1
8 Ω-1
9 Ω-1
12 Ω-1
As we learnt
Conductance -
Conductance
- wherein
Since volume of the wire does not change.
Þ l1A1 = l2 A2 where l1 and A1 are the initial length and cross-section of the wire, and l2 and A2 are the final length and cross-section.
Þ
C1 = A1/ρL1 and C2 = A2/ ρ L1
Þ C1/C2 = L22/L21 = 9
Þ C2= C1/9 = 8 Ω-1
Option 1)
6 Ω-1
Option 2)
8 Ω-1
Option 3)
9 Ω-1
Option 4)
12 Ω-1
Study 40% syllabus and score up to 100% marks in JEE