Question

A wire of resistance 3 ohm and length 30 cm. Assuming that it has a uniform cross section,what wil be it's new resistance​

Answer 1

• Resistance R=3 ohm

• New Length=30cm=3×I

• R=P× 1/A

new resistance with streching lenghth will increase & area of cross-section will decrease in the same.

• R=P×3/A/3

THEREFORE, R=9P×1/A=9R

• R=9×3=27n