In a $Ag$ voltameter,$2.68 \, g$ of silver is deposited in $10 \, \min$. The heat developed in a $20 \, \Omega$ resistor during the same period will be:

The figure shows a thick spherical shell made of a material with electrical conductivity $\sigma$. It has inner and outer radii of $10\ cm$ and $20\ cm$ respectively and is filled with ice inside. Its inner and outer surfaces are kept at different potentials by a battery with internal resistance $r = \frac{2}{\pi}\ \Omega$ and electromotive force $\epsilon = 5\ V$. Find the value of $\sigma$ for which the ice melts at the maximum possible rate,given that $25\%$ of the heat generated by the shell due to Joule heating is used to melt the ice.

Power dissipated across the $8 \,\Omega$ resistor in the circuit shown here is $2 \,\text{W}.$ The power dissipated in watt units across the $3 \,\Omega$ resistor is

An electric heater consists of a nichrome coil and runs under $220 \,V$,consuming $1 \,kW$ power. Part of its coil burned out and it was reconnected after cutting off the burnt portion. The power it will consume now is

If the current in an electric bulb is changed by $1\%$,then the percentage change in power will be ............. $\%$.

An expression for the rate of heat generated,if a current of $I$ ampere flows through a resistance of $R$ $\Omega$,is