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A capacitor of capacitance C is charged to a potential difference V from a cell and then disconnected from it . A charge +q is now given to its positive plate. the potential difference across the capacitor is

ARPAN BISWAS , 6 Years ago
Grade 12th pass
anser 2 Answers
Khimraj

Last Activity: 6 Years ago

initial condition
Q = CV
V = Q/C
final condition 
charge will redistribute and plates have charge Q + q/2 and -Q – q/2
so now V = (Q + q/2)/C = Q/C + q/2C = V + q/2C
Hope it clears.

Kushagra Madhukar

Last Activity: 4 Years ago

Dear student,
Please find the attached solution to your question.
 
Just after the cell is disconnected, the capicitor will have
Q = CV
V = Q/C
When +q charge is given to positively charged plate, it will redistribute and the plates would acquire the charges Q + q/2 and -Q – q/2 respectively.
Hence, The new potential difference across capacitor, V’ = (Q + q/2)/C = Q/C + q/2C = V + q/2C
 
Hope it helps.
Thanks and regards,
Kushagra

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