The heat produced per unit time,on passing electric current through a conductor at a given temperature,is directly proportional to . . . . . . .

How much energy in kilowatt-hour $(kWh)$ is consumed in operating ten $50\,W$ bulbs for $10$ hours per day in a month ($30$ days)?

$A$ potential $V_0$ is applied across a uniform wire of resistance $R$. The power dissipation is $P_1$. The wire is then cut into two equal halves and a potential of $V_0$ is applied across the length of each half. The total power dissipation across two wires is $P_2$. The ratio $P_2: P_1$ is $\sqrt{x}: 1$. The value of $x$ is $.............$.

Two bulbs of $250 \ V$ and $100 \ W$ are first connected in series and then in parallel with a supply of $250 \ V$. Total power in each of the cases will be . . . . . . respectively.

In the figure shown,the power generated in $y$ is maximum when $y = 5\,\Omega$. Then $R$ is

$A$ lamp of $60 \, W, 230 \, V$ is used for $8 \, \text{hours}$. If the cost of $1 \, \text{unit}$ is $1.25 \, \text{Rs}$, what will be the total bill in $Rs$?