Question

The resistance of a wire is$10 \Omega$. Its length is increased by 10% by stretching. The new resistance will now be

• A. $12 \Omega$
• B. $1.2 \Omega$
• C. $13 \Omega$
• D. $11 \Omega$

Answer 1

Answer: (A)

$12 \Omega$

Answer 2

Since $R \propto l ^ { 2 }$ ⇒ If length is increased by 10%, resistance is increases by almost 20%

Hence new resistance $R ^ { \prime } = 10 + 20 \%$of 10