Current Electricity Charging Discharging Of Capacitors Question 431
Question: A thick wire is stretched so that its length become two times. Assuming that there is no change in its density, then what is the ratio of change in resistance of wire to the initial resistance of wire
[MH CET 2004]
Options:
A) 2 : 1
B) 4 : 1
C) 3 : 1
D) 1 : 4
Show Answer
Answer:
Correct Answer: C
Solution:
In stretching $ R\propto l^{2} $
Therefore $ \frac{R _{2}}{R _{1}}=\frac{l _{2}^{2}}{l _{1}^{2}} $
Therefore $ \frac{R _{2}}{R _{1}}={{( \frac{2}{1} )}^{2}} $
Therefore $ R _{2}=4R _{1} $ . Change in resistance $ =R _{2}-R _{1}=3R _{1} $ Now, $ \frac{\text{Change}\text{in}\text{resistance}}{\text{Original}\text{resistance}}=\frac{3R _{1}}{R _{1}}=\frac{3}{1} $
BETA
