In the following circuit, $1 \,\Omega$ resistor dissipates power $P$. If the resistor is replaced by $9 \,\Omega$, the power dissipated in it is
$P$
$3 P$
$9 P$
$\frac{P}{3}$
Two wires have resistance of $2$ $\Omega$ and $4$ $\Omega$ connected to same voltage, ratio of heat dissipated at resistance is
An electric lamp is marked $60\, W$, $230\, V$. The cost of a $1\, kWh$ of energy is Rs. $1.25$. The cost of using this lamp $8$ hrs a day for $30$ day is Rs. ...............
When three identical bulbs of $60 \;W, 200\;V$ rating are connected in series to a $200 \;V$ supply, the power drawn by them will be ....... $Watt$
Model a torch battery of length $l$ to be made up of a thin cylindrical bar of radius $'a'$ and a concentric thin cylindrical shell of radius ' $b$ ' fille in between with an electrolyte of resistivity $\rho$ (see figure). If the battery is connected to a resistance of value $R ,$ the maximum Joule heating in $R$ will take place for
Three identical resistors $R_1=R_2=R_3$ are connected as shown to a battery of constant e.m.f. The power dissipated is ...........