The current flowing through a copper voltameter is $1.5\ A$. If the surface area of the electrode plate is $50\ cm^2$,the thickness of the copper layer deposited on this surface in $20\ min$ will be: (Density of copper = $9000\ kg/m^3$ and Electrochemical equivalent of copper = $0.00033\ g/C$)

$A$ 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 $= 1.118 \times 10^{-3}\,g/C$).

$A$ coil takes $15\,min$ to boil a certain amount of water,and another coil takes $20\,min$ for the same process. What is the time taken to boil the same amount of water when both coils are connected in series?

$A$ cell of emf $E$ has an internal resistance $r$ and is connected to a rheostat. When the resistance $R$ of the rheostat is changed,which is the correct graph of the potential difference $V$ across it?

Due to cold weather,a $1\, m$ water pipe of cross-sectional area $1\, cm^2$ is filled with ice at $-10^{\circ}C$. Resistive heating is used to melt the ice. $A$ current of $0.5\, A$ is passed through a $4\, k\Omega$ resistance. Assuming that all the heat produced is used for melting,what is the minimum time required? (In $s$)
(Given: latent heat of fusion for water/ice $= 3.33 \times 10^5\, J/kg$,specific heat of ice $= 2 \times 10^3\, J/(kg\cdot K)$ and density of ice $= 10^3\, kg/m^3$)

If for a thermocouple ${T_n}$ is the neutral temperature,${T_c}$ is the temperature of the cold junction,and ${T_i}$ is the temperature of inversion,then: