MCQ
A $16\  \Omega$ wire is bend to form a square loop. A $9 \mathrm{~V}$ battery with internal resistance $1\  \Omega$ is connected across one of its sides. If a $4\  \mu \mathrm{F}$ capacitor is connected across one of its diagonals, the energy stored by the capacitor will be $\frac{x}{2} \ \mu \mathrm{J}$. where $x=$________.
  • A
    $52$
  • B
    $42$
  • $81$
  • D
    $12$

Answer

Correct option: C.
$81$
c
$ I=\frac{V}{R_{e q}} I=\frac{V}{R_{e q}}=\frac{9}{1+\frac{12 \times 4}{12+4}}=\frac{9}{4} $

$ I_1=\frac{9}{4} \times \frac{4}{16}=\frac{9}{16} $

$ V_A-V_B=I_1 \times 8=\frac{9}{16} \times 8=\frac{9}{2} V $

$ \therefore U=\frac{1}{2} \times 4 \times \frac{81}{4} \mu \mathrm{J} $

$ \therefore U=\frac{81}{2} \mu \mathrm{J} $

$ \therefore \mathrm{X}=81$

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