Charge on capacitor plates without the dielectric is
=CV=(5×10−6F)×1V=5×10−6C=5μC
The capacitance after the dielectric is introduced is
C′=ε0Ad−(t−tK)=ε0A/d1−⎛⎜
⎜
⎜⎝t−tKd⎞⎟
⎟
⎟⎠=C1−⎛⎜
⎜
⎜⎝t−tKd⎞⎟
⎟
⎟⎠=5μF1−⎛⎜
⎜
⎜⎝4cm−4cm46cm⎞⎟
⎟
⎟⎠=5μF1−(4−16)=10μF
∴ Charge on capacitor plate now will be
Q′=C′V=10μF×1V=10μC
Additional charge transferred =Q′−Q=10μC−5μC=5μC