A potential $\mathrm{V}_{0}$ is applied across a uniform wire of resistance $R$. The power dissipation is $P_{1}$. The wire is then cut into two equal halves and a potential of $V_{0}$ is applied across the length of each half. The total power dissipation across two wires is $P_{2}$. The ratio $P_{2}: \mathrm{P}_{1}$ is $\sqrt{x}: 1$. The value of $x$ is ___________.
Solution
Let's analyze the initial situation where the potential $V_0$ is applied across the entire length of the wire with resistance $R$.
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The power dissipation, $P_1$, can be calculated using the formula:
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$P_1 = \frac{V_0^2}{R}$
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Now, let's consider the case where the wire is cut into two equal halves. Each half will have half the original resistance, $\frac{R}{2}$. The potential $V_0$ is applied across the length of each half.
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For each half of the wire, the power dissipation, $P'$, can be calculated using the formula:
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$P' = \frac{V_0^2}{\frac{R}{2}} = \frac{2V_0^2}{R}$
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Since there are two halves of the wire, the total power dissipation across the two wires, $P_2$, is:
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$P_2 = 2P' = 2\left(\frac{2V_0^2}{R}\right) = \frac{4V_0^2}{R}$
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Now, let's find the ratio $P_2 : P_1$:
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$\frac{P_2}{P_1} = \frac{\frac{4V_0^2}{R}}{\frac{V_0^2}{R}} = 4$
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Comparing this to the given ratio $\sqrt{x} : 1$, we have:
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$\frac{P_2}{P_1} = \sqrt{x}$
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So, $\sqrt{x} = 4$.
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Squaring both sides, we get:
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$x = 16$
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The value of $x$ is 16.
About this question
Subject: Physics · Chapter: Current Electricity · Topic: Ohm's Law and Resistance
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