Two electric lamps of $40\, W$ each are connected in parallel. The power consumed by the combination will be ........... $W$.

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?

Which of the following plots may represent the thermal energy produced in a resistor in a given time as a function of the electric current?

$A$ constant voltage is applied between two ends of a metallic wire. If the length is halved and the radius of the wire is doubled,the rate of heat developed in the wire will be

$A$ light bulb is rated at $200 \text{ W}$ for a $220 \text{ V}$ supply. Find the resistance of the bulb. (in $\Omega$)

$A$ resistance $R = 12 \, \Omega$ is connected across a source of $emf$ as shown in the figure. Its $emf$ changes with time as shown in the graph. What is the heat developed in the resistance in the first four seconds (in $, J$)?