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
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 \[R=\frac{(\text{Thickness})}{(\text{Area of cross }\,\text{section})}\] = \[27\times {{10}^{-9}}\pi \times \frac{({{10}^{-3}})}{\pi \times {{(1\times {{10}^{-2}})}^{2}}}\]\[=2.7\times {{10}^{-7}}\Omega .\]
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