$A$ $12 \text{ HP}$ motor has to be operated $8 \text{ hours/day}$. How much will it cost at the rate of $50 \text{ paisa/kWh}$ in $10$ days? (in $Rs.$)

The ratio of cross-sectional areas of two conducting wires made up of the same material and having the same length is $1 : 2$. What will be the ratio of heat produced per second in the wires,when the same current is flowing in them?

$A$ heater draws a current of $2\,A$ when connected to a $250\,V$ source. The rate of energy dissipation is ............. $W$.

$A$ coil develops heat of $800 \, cal/sec$ when $20 \, V$ is applied across its ends. The resistance of the coil is .............. $\Omega$ $(1 \, cal = 4.2 \, J)$.

$A$ $500\, W$ heating unit is designed to operate from a $115\, V$ line. If the line voltage drops to $110\, V$,the percentage drop in heat output will be ............... $\%$

$A$ lamp is rated at $240 \ V, 60 \ W$. When in use,the resistance of the filament of the lamp is $20$ times that of the cold filament. The resistance of the lamp when not in use is: (in $\Omega$)