The heat developed in an electric wire of resistance $R$ by a current $I$ for a time $t$ is
$\frac{{{I^2}Rt}}{{4.2}}cal$
$\frac{{{I^2}t}}{{4.2R}}cal$
$\frac{{{I^2}R}}{{4.2\,t}}cal$
$\frac{{Rt}}{{4.2\,{I^2}}}cal$
Of the two bulbs in a house hold circuit, one glows brighter than the other, Which of the two bulbs has a large resistance?
In the following circuit, $1 \,\Omega$ resistor dissipates power $P$. If the resistor is replaced by $9 \,\Omega$, the power dissipated in it is
The two bulbs as in the above question are connected in series to a $200\, volt$ line. Then
A $5\,^oC$ rise in temperature is observed in a conductor by passing a current. When the current is doubled the rise in temperature will be approximately ........... $^oC$
If a $30\, V$, $90\, W$ bulb is to be worked on a $120\, V$ line, a resistance of how many ohms should be connected in series with the bulb ............... $ohm$