If two bulbs of wattage $25$ and $30$, each rated at $220\, volts$, are connected in series with a $440$ $volt$ supply, which bulb will fuse

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

A filament bulb $(500 \,W,\,\, 100 \,V)$ is to be used in a $230\, V$ main supply. When a resistance $R$ is connected in series, it works perfectly and the bulb consumes $500\,W.$ The value of $R$ is .................. $\Omega$

Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is

Two resistors having equal resistances are joined in series and a current is passed through the combination. Neglect any variation in resistance as the temperature changes. In a given time interval

Two electric bulbs marked $40\,W,$ $220\,V$ and $60\,W,\,\,220\,V$ when connected in series across same voltage supply of $220\,V,$ the effective power is $P_1$ and when connected in parallel, the effective power is $P_2.$ Then $\frac {P_1}{P_2}$ is