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?

$A$ 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 $..... \, J$.

By what percentage will the illumination of the lamp decrease if the current drops by $20 \%$ (in $\%$)?

You are given three bulbs of $25\, W$,$40\, W$,and $60\, W$. Which of them has the lowest resistance?

An electric heater rated $220 \,V$ and $550 \,W$ is connected to $AC$ mains. The current drawn by it is (in $\,A$)

Two electric bulbs rated $P_1 \text{ watt}, V \text{ volts}$ and $P_2 \text{ watt}, V \text{ volts}$ are connected in parallel and $V \text{ volts}$ are applied to the combination. The total power consumed will be: