Ch$26$:

When a potential difference of $15$ V is applied to the plates of an air filled$-$parallel plate capacitor $(C_1),$ the plates carry a charge of $45C.$

What is the capacitance of the capacitor $C_1?$

If the capacitor $C_1$ is connected to another capacitor $C_2=15\mathrm{.}0F$ as shown, what is the equivalent capacitance of the combination?

If $C_1$ is filled with Teflon, where $k_{\text{T}\text{e}\text{f}\text{l}\text{o}\text{n}}=2\mathrm{.}1.$ What will be its new capacitance?

Ch$27$:

The quantity of charge $($in Coulombs$)$ that has passed through a surface varies as: $q(t)=t^2+8t,$ where $t$ is in seconds. What is the instantaneous current at $t=5s?$

The power of a certain device is rated at $2\mathrm{.}5$ kW when connected to a $120$ V source. What is the resistance of the device?