Question

An air capacitor of capacity $C=10\mu F$ is connected to a constant voltage battery of $12$ volt. Now the space between the plates is filled with a liquid of dielectric constant $5$. The (additional) charge that flows now from battery to the capacitor is :

• A. $120\mu C$
• B. $600\mu C$
• C. $480\mu C$
• D. $24\mu C$

Answer 1

Answer: (C)

$480\mu C$

Initial charge $q_i=CV=10\left(12\right)=120\mu C$.
After filled with dielectric liquid the charge $q^{\prime }=C^{\prime }V=KCV=5\left(10\right)12=600\mu C$
The (additional) charge that flows now from battery to the capacitor $=q_f-q_i=600-120=480\mu C$