A wire of 3Ω resistance and 15cm in length is stretched to 45 cm length. Calculate (i) New resistance.
Assuming the wire has uniform cross section area.
Given:
Resistance R = 3Ω
Original length L1 = 15cm = 0.15m
New length, L2 = 45 cm = 0.45 m
Formula Used:
Where, ρ is resistivity of the wire
L is the length of the wire
A is the area of the wire.
Now, 
⇒ 
⇒ 
⇒ R2 = 9 Ω
Hence, the new resistance is 9 Ω
15