Assertion: Charges are given to plates of two plane parallel plate capacitors `C_(1)` and `C_(2)` (such that `C_(2) = 2C_(1))` as shown in figure. Then the key `K` is pressed to complate the circuit. Finally the net charge on upper plate and net charge on lower plate of capacitor `C_(1)` is positive.

Reason: In a parallel plate capacitor both plates always carry equal and opposite charge.

Options

A. If both assertion and reason are true and reson is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion and reason both are false.

Answer

C

Explanation

In isolated condition the charge distribution on each surface of capacitor `C_(1)` and `C_(2)` is

The `p.d.` across first capacitor is `(q_(1))/(C_(1)) = (1muF)/(C_(1))`
The `p.d` across second capacitor is `(q_(2))/(C_(2)) = (2muF)/(C_(2))`
Hence potential difference across both the capacitors is same (hence `C_(2) = 2C_(1)`). therefore on connecting both capacitors, charges, charge does not flow from one capacitor to other. Therefore net charge on upper and lower plates of `C_(1)` is positive.
Hence Assertion is true and Reason is false.