Current in the circuit, $\mathrm{I}=\frac{2}{5}=0.4 \mathrm{\,A}$
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Water boils in an electric kettle in $20$ minutes after being switched on. Using the same main supply, the length of the heating element should be. . . . . . .to . . . . . .. times of its initial length if the water is to be boiled in $15$ minutes.
Current density in a cylindrical wire of radius $R$ is given as $J =$ $\left\{ {\begin{array}{*{20}{c}}
{{J_0}\left( {\frac{x}{R} - 1} \right)\,\,for\,\,0 \leqslant x < \frac{R}{2}} \\
{{J_0}\frac{x}{R}\,\,\,\,for\,\,\,\frac{R}{2} \leqslant x \leqslant R}
\end{array}} \right.$The current flowing in the wire is:
Two wires $A$ and $B$ are made up of the same material and have the same mass. Wire A has radius of $2.0 \mathrm{~mm}$ and wire $B$ has radius of $4.0 \mathrm{~mm}$. The resistance of wire B is $2 \Omega$. The resistance of wire $\mathrm{A}$ is_______. $\Omega$.
The charge flowing through a resistance $R$ varies with time according to $Q = at -bt^2.$ The total heat produced in $R$ is : (assume that direction of current not reversed)
The resistances in $WSB$ circuit shown in the diagram all are different and the current through the galvanometer is zero. If all thermal effects are negligible, the current through the galvanometer will not be zero, when
A $220\, volt$ and $800\, watt$ electric kettle and three $220\, volt$ and $100\, watt$ bulbs are connected in parallel. On connecting this combination with $220\, volt$ electric supply, the total current will be ................ $ampere$