Electrostatic Potential and Capacitance - Result Question 45

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47. If the potential of a capacitor having capacity $6 \mu F$ is increased from $10 V$ to $20 V$, then increase in its energy will be

======= ####47. If the potential of a capacitor having capacity $6 \mu F$ is increased from $10 V$ to $20 V$, then increase in its energy will be

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(b) $4 \times 10^{-4} J$

(c) $9 \times 10^{-4} J$

(d) $12 \times 10^{-6} J$

[1995]

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Answer:

Correct Answer: 47. (c)

Solution:

  1. (c) Capacitance of capacitor $(C)=6 \mu F=6$ $\times 10^{-6} F$; Initial potential $(V_1)=10 V$ and final potential $(V_2)=20 V$.

The increase in energy $(\Delta U)$

$=\frac{1}{2} C(V_2^{2}-V_1^{2})$

$=\frac{1}{2} \times(6 \times 10^{-6}) \times[(20)^{2}-(10)^{2}]$

$=(3 \times 10^{-6}) \times 300=9 \times 10^{-4} J$.