A circuit consists of a current source of emf $\epsilon$ and internal resistance $r$, capacitors of capacitance $C_1$ and $C_2$, and resistors of resistance $R_1$ and $R_2$.

Determine the voltages $U_1$ and $U_2$ across each capacitor.

A perfect voltmeter and a perfect ammeter are connected in turn between points $E$ and $F$ of a circuit whose diagram is shown in Fig. The readings of the instruments are $U_0$ and $I_0$. 

Determine the current $I$ through the resistor of resistance $R$ connected between points $E$ and $F$.

A plate $A$ of a parallel-plate capacitor is fixed, while a plate $B$ is attached to the wall by a spring and can move, remaining parallel to the plate $A$. After the key $K$ is closed, the plate $B$ starts moving and comes to rest in a new equilibrium position. The initial equilibrium separation $d$ between the plates decreases in this case by $10\%$.

What will be the decrease in the equilibrium separation between the plates if the key $K$ is closed for such a short time that the plate $B$ cannot be shifted noticeably?

The circuit shown in is made of a homogeneous wire of constant cross section.

Find the ratio $\frac{Q_{12}}{Q_{34}}$ of the amounts of heat liberated per unit time in conductors $1-2$ and $3-4$.

The voltage between the anode and the cathode of a vacuum-tube diode is $U$ and the anode current is $I$.

Determine the mean pressure $p_{\mathrm{m}}$ of electrons on the anode surface of area $S$.

across the capacitor plates varies as shown in the figure Plot the time dependence of voltage across the clamps $CD$.

Two batteries of emf ${\epsilon }_1$ and ${\epsilon }_2$, a capacitor of capacitance $C$, and a resistor

of resistance $R$ are connected in a circuit as shown in Fig. 

Determine the amount of heat $Q$ liberated in the resistor after switching the key $\overrightarrow{K}$.

An electric circuit consists of a current source of emf $\epsilon$ and internal resistance $r$, and two resistors connected in parallel to the source (Fig.). The resistance $R_1$ of one resistor remains unchanged, while the resistance $R_2$ of the other resistor can be chosen so that the power liberated in this resistor is maximum.

Determine the value of $R_2$ corresponding to the maximum power.

A capacitor of capacitance $C_1$ is discharged through a resistor of resistance $R$.

When the discharge current attains the value $I_{0,}$ the key $K$is opened.

Determine the amount of heat $Q$ liberated in the resistor starting from this moment.