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.

Which of the following graphs correctly represents the variation of heat energy $(U)$ produced in a metallic conductor in a given time as a function of potential difference $(V)$ across the conductor?

$A$ student in a town in India,where the price per unit $(1 \text{ unit} = 1 \,kWh)$ of electricity is $₹ 5.00$,purchases a $1 \,kVA$ $UPS$ (uninterrupted power supply) battery. $A$ day before the exam,$10$ friends arrive at the student's home with their laptops and all connect their laptops to the $UPS$. Assume that each laptop has a constant power requirement of $90 \,W$. Consider the following statements.
$I.$ All the $10$ laptops can be powered by the $UPS$,if connected directly.
$II.$ All the $10$ laptops can be powered,if connected using an extension box with a $3 \,A$ fuse.
$III.$ If all the $10$ friends use the laptop for $5 \,h$,then the cost of the consumed electricity is about $₹ 22.50$.
Select the correct option with the true statements.

How many units are consumed if a $100\,W$ electric bulb is kept $ON$ for $10$ hours?

$A$ resistor dissipates $192 \, J$ of energy in $1 \, s$ when a current of $4 \, A$ is passed through it. Now,when the current is doubled,the amount of thermal energy dissipated in $5 \, s$ is $..... \, J$.

$A$ heater of $220\, V$ heats a volume of water in $5\, \text{min}$ time. $A$ heater of $110\, V$ heats the same volume of water in ............... $\text{min}$.