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QJEEM23Phfaba: JEE Main 2023 Physics - Class 12 JEEM23Phfaba Solution: A potential is applied across a uniform wire of resistance .…

A potential V0\mathrm{V}_{0} is applied across a uniform wire of resistance RR . The power dissipation is P1P_{1} . The wire is then cut into two equal halves and a potential of V0V_{0} is applied across the length of each half. The total power dissipation across two wires is P2P_{2} . The ratio P2:P1P_{2}: \mathrm{P}_{1} is x:1\sqrt{x}: 1 . The value of xx is ___________.

Step-by-Step Verified Solution

Let's analyze the initial situation where the potential V0V_0 is applied across the entire length of the wire with resistance RR .

The power dissipation, P1P_1 , can be calculated using the formula:

P1=V02RP_1 = \frac{V_0^2}{R}

Now, let's consider the case where the wire is cut into two equal halves. Each half will have half the original resistance, R2\frac{R}{2} . The potential V0V_0 is applied across the length of each half.

For each half of the wire, the power dissipation, P′P' , can be calculated using the formula:

P′=V02R2=2V02RP' = \frac{V_0^2}{\frac{R}{2}} = \frac{2V_0^2}{R}

Since there are two halves of the wire, the total power dissipation across the two wires, P2P_2 , is:

P2=2P′=2(2V02R)=4V02RP_2 = 2P' = 2\left(\frac{2V_0^2}{R}\right) = \frac{4V_0^2}{R}

Now, let's find the ratio P2:P1P_2 : P_1 :

P2P1=4V02RV02R=4\frac{P_2}{P_1} = \frac{\frac{4V_0^2}{R}}{\frac{V_0^2}{R}} = 4

Comparing this to the given ratio x:1\sqrt{x} : 1 , we have:

P2P1=x\frac{P_2}{P_1} = \sqrt{x}

So, x=4\sqrt{x} = 4 .

Squaring both sides, we get:

x=16x = 16

The value of xx is 16.

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