Current Electricity Charging Discharging Of Capacitors Question 352
Question: The resistance of a wire of uniform diameter $ d $ and length $ L $ is $ R $ . The resistance of another wire of the same material but diameter $ 2d $ and length $ 4L $ will be
[CPMT 1984; MP PET 2002]
Options:
A) $ 2R $
B) $ R $
C) $ R/2 $
D) $ R/4 $
Show Answer
Answer:
Correct Answer: B
Solution:
$ R\propto \frac{l}{A}\propto \frac{l}{d^{2}} $
Therefore $ \frac{R _{1}}{R _{2}}=\frac{l _{1}}{l _{2}}\times ,{{( \frac{d _{2}}{d _{1}} )}^{2}}=\frac{L}{4L},{{( \frac{2d}{d} )}^{2}}=1 $
Therefore $ R _{2}=R _{1}=R. $
BETA
