Current Electricity Charging Discharging Of Capacitors Question 684
Question: A wire X is half the diameter and half the length of a wire Y of similar material. The ratio of resistance of X to that of Y is
Options:
A) 8 : 1
B) 4 : 1
C) 2 : 1
D) 1 : 1
Show Answer
Answer:
Correct Answer: C
Solution:
[c] $ R=\frac{\rho \ell }{(\pi D^{2}/4)}\text{or }R\propto \frac{\ell }{D^{2}}. $
$ \frac{R _{x}}{R _{y}}=\frac{{\ell _{x}}}{D _{x}^{2}}\times \frac{D _{y}^{2}}{{\ell _{y}}}=\frac{{\ell _{y}}/2}{{{(D _{y}/2)}^{2}}}\times \frac{D _{y}^{2}}{{\ell _{y}}}=\frac{2}{1} $
BETA
