Current Electricity Charging Discharging Of Capacitors Question 676
Question: The resistance of a wire is R. It is bent at the middle by $ 180{}^\circ $ and both the ends are twisted together to make a shorter wire. The resistance of the new wire is
Options:
A) 2R
B) R/2
C) R/4
D) R/8
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Resistance of wire (R) $ =\rho \frac{\ell }{A} $ If wire is bent in the middle then $ \ell ‘=\frac{\ell }{2},A’=2A $
$ \
Therefore $ New resistance, $ R’=\rho \frac{\ell ‘}{A’}=\frac{\rho \frac{\ell }{2}}{2A} $
$ =\frac{\rho \ell }{4A}=\frac{R}{4}. $
BETA
