Verified Solution • 2025–26 Session
moderate
QNEET-2013-Ph-1528: NEET 2013 Physics - Class 12 NEET-2013-Ph-1528 Solution: A wire of resistance \(4 \) is stretched to twice its original…
A wire of resistance is stretched to twice its original length. The resistance of stretched wire would be
Multiple Choice Options
- A 8 �
- B 16 �
- C 2 �
- D 4 �
Step-by-Step Verified Solution
Resistance of a wire,
R = _ l A = 4 � ...(i)
When wire is stretched twice, its new length be l _ . Then
l _ = 2 l
On stretching volume of the wire remains constant.
_ l A = l _ A _ where A' is the new cross-sectional area
_ A _ = l l _ A = l 2 l A = A 2
_ Resistance of the stretched wire is
R _ = _ l _ A _ = _ 2 l ( A / 2 ) = 4 _ l A
= 4 ( 4 � ) = 16 �