| ASSERTION: When a wire is stretched to three times its length, its resistance becomes 9 times. |
| REASON: Resistance is directly proportional to length of wire. |
A) If both assertion and reason are true and reason is the correct explanation of assertion.
B) If both assertion and reason are true and reason is not the correct explanation of assertion.
C) If assertion is true but reason is false.
D) If both assertion and reason are false.
E) If assertion is false but reason is true.
Correct Answer: A
Solution :
Volume of material on stretching remains same. i.e., \[Al\]= constant. When l becomes 3 times, its area of cross section [A] becomes l/3rd. From \[R=\rho \frac{l}{A}\]. R would becomes 9 times.
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