Current Electricity Charging Discharging Of Capacitors Question 396
Question: A rod of a certain metal is 1.0 m long and 0.6 cm in diameter. Its resistance is 3.0 × $ {{10}^{-3}} $ ohm. Another disc made of the same metal is 2.0 cm in diameter and 1.0 mm thick. What is the resistance between the round faces of the disc
[MP PET 2000]
Options:
A) $ \text{1}.\text{35 }\times ~{{10}^{-8}}hm $
B) 2.70 × $ {{10}^{-7}} $ ohm
C) 4.05 × $ {{10}^{-6}} $ ohm
D) 8.10 × $ {{10}^{-5}} $ ohm
Show Answer
Answer:
Correct Answer: B
Solution:
Resistivity of the material of the rod $ \rho =\frac{RA}{l}=\frac{3\times {{10}^{-3}}\pi {{(0.3\times {{10}^{-2}})}^{2}}}{1} $ = $ 27\times {{10}^{-9}}\pi ,\Omega \times m $ Resistance of disc $ R=\frac{(\text{Thickness})}{(\text{Area of cross },\text{section})} $ = $ 27\times {{10}^{-9}}\pi \times \frac{({{10}^{-3}})}{\pi \times {{(1\times {{10}^{-2}})}^{2}}} $
$ =2.7\times {{10}^{-7}}\Omega . $
BETA
