Q130 / 160 · TS EAMCET 2012 · Physics

Three resistances of equal values are arranged in four different configurations as shown below. Power dissipation in the increasing order is Figure
Figure
Figure
Figure

  • Correct answer
    A
    (III) $ < $ (II) $ < $ (IV) $ < $ (I)
  • B
    (II) $ < $ (III) $ < $ (IV) $ < $ (I)
  • C
    (I) $ < $ (IV) $ < $ (III) $ < $ (II)
  • D
    (I) $ < $ (III) $ < $ (II) $ < $ (IV)

Solution

For figure I, $\begin{aligned} \text { Total resistance } & =3 R \\ \text { I power } & =I^2(3 R)\end{aligned}$ For figure II, $\begin{aligned} \text { Resistance } & =\frac{2 R}{3} \Omega \\ \text { II power } & =I^2\left(\frac{2 R}{3}\right)\end{aligned}$ For figure III, $\begin{aligned} \text { Total resistance } & =\frac{R}{3} \Omega \\ \text { III power } & =I^2\left(\frac{R}{3}\right)\end{aligned}$ For figure IV, Total resistance $\frac{3}{2} \Omega$ IV power $=I^2\left(\frac{3}{2} R\right)$ Hence, option (a) is correct.

Hence, the correct answer is option: 'A'.

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