A rectangular parallelopiped is measured as $1 \mathrm{~cm} \times 1 \mathrm{~cm} \times 100 \mathrm{~cm}$. If its specific resistance is $3 \times 10^{-7} ~\Omega \mathrm{m}$, then the resistance between its two opposite rectangular faces will be ___________ $\times 10^{-7} ~\Omega$.
Answer (integer)
3
Solution
<p>The resistance of a material can be calculated using the formula:</p>
<p>$ R = \rho \frac{L}{A} $</p>
<p>where </p>
<ul>
<li>$R$ is the resistance, </li>
<li>$\rho$ (rho) is the resistivity or specific resistance of the material, </li>
<li>$L$ is the length (or distance over which the resistance is being measured), and </li>
<li>$A$ is the cross-sectional area through which the current flows.</li>
</ul>
<p>In the context of a rectangular parallelepiped, the "length" and "cross-sectional area" can vary depending on which faces of the shape are considered.</p>
<p>In this particular calculation, the resistance is being measured between the two smaller faces of the parallelepiped, which are squares of side length 1 cm:</p>
The cross-sectional area $A$ should be:
<br/><br/>
$A = 100 \, \text{cm} \times 1 \, \text{cm} = 100 \, \text{cm}^2$
<br/><br/>
Converting this to meters gives:
<br/><br/>
$A = 100 \, \text{cm}^2 = 1 \, \text{m} \times 0.01 \, \text{m} = 0.01 \, \text{m}^2$
<br/><br/>
So, if we use these values for the length $L$ and cross-sectional area $A$ in the resistance formula, we get:
<br/><br/>
$ R = \rho \frac{L}{A} = 3 \times 10^{-7} \Omega \, m \times \frac{0.01 \, m}{0.01 \, \text{m}^2} = 3 \times 10^{-7} \Omega $
<p>Therefore, the resistance between the two smaller faces of the rectangular parallelepiped is $3 \times 10^{-7} \Omega$.</p>
About this question
Subject: Physics · Chapter: Current Electricity · Topic: Ohm's Law and Resistance
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