In a copper voltameter,the mass deposited in $6 \text{ min}$ is $m \text{ g}$. If the current-time graph for the voltameter is as shown in the figure,then the $E.C.E.$ of the copper is:

In an electroplating experiment,a current of $4 \ A$ is passed for $2 \ min$ to deposit a mass $m$ of silver. If a current of $6 \ A$ is passed for $40 \ s$,the mass of silver deposited is:

For the circuit shown in the figure:
$(A)$ The current $I$ through the battery is $7.5 \text{ mA}$.
$(B)$ The potential difference across $R_L$ is $18 \text{ V}$.
$(C)$ The ratio of powers dissipated in $R_1$ and $R_2$ is $3$.
$(D)$ If $R_1$ and $R_2$ are interchanged,the magnitude of the power dissipated in $R_L$ will decrease by a factor of $9$.

For a thermocouple,the temperature of inversion is that temperature at which the thermo $e.m.f.$ is:

Six similar bulbs are connected as shown in the figure with a $DC$ source of $emf\; E$,and zero internal resistance. The ratio of power consumption by the bulbs when $(i)$ all are glowing and $(ii)$ in the situation when two from section $A$ and one from section $B$ are glowing,will be

In steady state, a capacitor of capacitance $2 \mu F$ is charged to $4 \mu C$, as shown in the figure. If the internal resistance of the cell is $0.5 \Omega$, then the emf of the cell is (in $\text{V}$)