$A$ battery is charged by a $15\,V$ battery for $8\,h$ at a current of $10\,A$. When this battery discharges, it provides a current of $5\,A$ for $15\,h$. The average terminal voltage during discharge is $14\,V$. What is the $watt-hour$ efficiency of this battery in $\%$?

$A$ silver and a copper voltameter are connected in parallel across a $6\,V$ battery of negligible resistance. In half an hour,$1\,g$ of copper and $2\,g$ of silver are deposited. The rate at which energy is supplied by the battery will approximately be ............... $W$ (Given $E.C.E.$ of copper $= 3.294 \times 10^{-4}\,g/C$ and $E.C.E.$ of silver $= 1.118 \times 10^{-3}\,g/C$).

The $V-i$ graphs for a conductor at temperatures $T_1$ and $T_2$ are shown. $(T_2 - T_1)$ is proportional to:

$A$ copper voltameter is connected in series with a heater coil of resistance $0.1\,\Omega$. $A$ steady current flows in the circuit for $20$ minutes and a mass of $0.99\,g$ of copper is deposited at the cathode. If the electrochemical equivalent of copper is $0.00033\,g/C$, then the heat generated in the coil is ............... $J$.

The two ends of a conductor are connected to a cell having an $e.m.f. \ E$ and some internal resistance. Starting from the midpoint $P$ of the conductor,moving in the direction of the current,and returning to point $P$,which of the following graphs best represents the potential $V$ versus the distance $x$ covered along the path?

$A$ uniform metallic wire of length $L$ is mounted in two configurations. In configuration $1$ (triangle),it is an equilateral triangle and a voltage $V$ is applied to corners $A$ and $B$. In configuration $2$ (circle),it is bent in the form of a circle and the potential $V$ is applied at diametrically opposite points $P$ and $Q$. The ratio of the power dissipated in configuration $1$ to configuration $2$ is