Manipal Entrance Test 2020 Physics Paper

As the battery remains connected. potential difference (V) of the capacitor remains constant. Suppose dielectric of dielectric constant K is introduced between the plates. Now, capcitance of the capacitor is
C′=KC0
where, C0 is original capacitance.
Initial energy stored in the capacitor
Ui=‌

1

2

C0V2
Final energy stored in the capacitor
Uf=‌

1

2

C′V2=‌

1

2

(KC0)V2
Clearly, ‌‌‌

Uf

Ui

=K>1⇒Uf>Ui
As, ‌‌Q=CV
∴V remains constant and C increases.
∴Q increases.