Electrostatic Potential and Capacitance - Result Question 42

44. A capacitor is charged to store an energy U. The charging battery is disconnected. An identical capacitor is now connected to the first capacitor in parallel. The energy in each of the capacitor is

(a) U/2

(b) 3U/2

(c) U

(d) U/4

[2000]

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Answer:

Correct Answer: 44. (d)

Solution:

  1. (d) In first case, when capacitor C connected with battery.

Energy stored, u1=12CV2=12Q2C

When battery is disconnected and another capacitor of same capacity is connected in parallel to first capacitor, then

Ceq =C=2C

Voltage across each capacitor, V=Q2C

Energy stored, V2=12CV2

=12C(Q2C)2=1412Q2C=U14



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