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Standard XII

Physics

EMF and EMF Devices

A cell of emf...

Question

A cell of emf $E$ volts with no internal resistance is connected to a wire of uneven cross-sectional area. The wire has three sections of equal length. The radius of the middle section is $a$ and the other are $2 a$ . The ratio of the potential difference across the middle section to any other section is

2 : 1

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4 : 1

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1 : 2

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1 : 4

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Solution

The correct option is D $4 : 1$
In series $I$ is same
So,V $\propto R \propto \frac{1}{r^{2}}$
So, $\frac{V_{t h i n}}{V_{t h i c k}} = (\frac{r_{t h i c k}}{r_{t h i n}})^{2} = (\frac{2}{1})^{2} = 4 : 1$

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A cell of emf E volts with no internal resistance is connected to a wire of uneven cross-sectional area. The wire has three sections of equal length. The radius of the middle section is a and the other are 2a. The ratio of the potential difference across the middle section to any other section is

The correct option is D 4:1In series I is sameSo,V∝R∝1r2So,VthinVthick=(rthickrthin)2=(21)2=4:1

The correct option is D $4 : 1$
In series $I$ is same
So,V $\propto R \propto \frac{1}{r^{2}}$
So, $\frac{V_{t h i n}}{V_{t h i c k}} = (\frac{r_{t h i c k}}{r_{t h i n}})^{2} = (\frac{2}{1})^{2} = 4 : 1$