If $96500 \ C$ of charge deposits $1 \ g$ of a substance,how much time will it take to deposit $20 \ mg$ of copper from a copper sulfate solution using a current of $0.15 \ A$?

$A$ uniform metallic wire carries a current of $2\,A$ when a $3.4\,V$ battery is connected across it. The mass of the uniform metallic wire is $8.92 \times 10^{-3}\,kg$,its density is $8.92 \times 10^3\,kg/m^3$,and its resistivity is $1.7 \times 10^{-8}\,\Omega\cdot m$. The length of the wire is $l = \dots\dots\dots\dots\,m$.

If two bulbs of wattage $25\, W$ and $100\, W$ respectively,each rated at $220\, V$,are connected in series with a supply of $440\, V$,then which bulb will fuse?

Suppose there is a circuit consisting of only resistances and batteries. Suppose one is to double (or increase it to $n$-times) all voltages and all resistances. Show that currents are unaltered.

The smallest temperature difference that can be measured with a combination of a thermocouple of thermo $e.m.f.$ $30\,\mu V$ per degree and a galvanometer of $50\,\Omega$ resistance,capable of measuring a minimum current of $3 \times 10^{-7} \, A$ is ............... $^\circ C$.

One end of a Nichrome wire of length $2L$ and cross-sectional area $A$ is attached to an end of another Nichrome wire of length $L$ and cross-sectional area $2A$. If the free end of the longer wire is at an electric potential of $8.0\,V$,and the free end of the shorter wire is at an electric potential of $1.0\,V$,the potential at the junction of the two wires is equal to ............. $V$.