Current Electricity Charging Discharging Of Capacitors Question 342
Question: A wire of length 5 $ m $ and radius 1 $ mm $ has a resistance of 1 ohm. What length of the wire of the same material at the same temperature and of radius 2 $ mm $ will also have a resistance of 1 ohm
Options:
A) 1.25 $ m $
B) 2.5 $ m $
C) 10 $ m $
D) 20 $ m $
Show Answer
Answer:
Correct Answer: D
Solution:
$ R\propto \frac{l}{r^{2}} $
$ \Rightarrow $ $ \frac{R _{1}}{R _{2}}=\frac{l _{1}}{l _{2}}\times \frac{r _{2}^{2}}{r _{1}^{2}}\Rightarrow \frac{1}{1}=\frac{5}{l _{2}}\times {{( \frac{2}{1} )}^{2}}\Rightarrow l _{2}=20m $
BETA
