An electric bulb rated $50 \mathrm{~W}-200 \mathrm{~V}$ is connected across a $100 \mathrm{~V}$ supply. The power dissipation of the bulb is :
$12.5 \mathrm{~W}$
$25 \mathrm{~W}$
$50 \mathrm{~W}$
$100 \mathrm{~W}$
If power in external resistance $R$ is maximum then
$(i) R = r$ $(ii)$ Power in $R$ is $\frac{{{E^2}}}{{4R}}$
$(iii)$ Input power $\frac{{{E^2}}}{{2R}}$ $(iv)$Efficiency is $50\%$
You are given a resistance wire of length $50\, cm$ and a battery of negligible resistance. In which of the following cases is largest amount of heat generated
Which of the four resistances $P, Q, R$ and $S$ generate the greatest amount of heat when a current flows from $A$ to $B$ ?
For driving a current of $2\, A$ for $6$ minutes in a circuit, $1000\, J$ of work is to be done. The $e.m.f.$ of the source in the circuit is ................ $V$
Two cities are $150\,\, km$ apart. Electric power is sent from one city to another city through copper wires. The fall of potential per $km$ is $8\,\, volt$ and the average resistance per km is $0.5 \,\,\Omega .$ The power loss in the wire is