Current Electricity Charging Discharging Of Capacitors Question 394
Question: Equal potentials are applied on an iron and copper wire of same length. In order to have the same current flow in the two wires, the ratio r (iron)/r (copper) of their radii must be (Given that specific resistance of iron = $ 1.0\times {{10}^{-7}} $ ohm?m and specific resistance of copper = $ 1.7\times {{10}^{-8}} $ ohm-m)
[MP PMT 2000]
Options:
A) About 1.2
B) About 2.4
C) About 3.6
D) About 4.8
Show Answer
Answer:
Correct Answer: B
Solution:
$ \frac{{r _{\text{iron}}}}{{r _{\text{Copper}}}}=\sqrt{\frac{{\rho _{\text{iron}}}}{{\rho _{\text{copper}}}}}=\sqrt{\frac{1\times {{10}^{-7}}}{1.7\times {{10}^{-8}}}}\approx 2.4 $ .
BETA
