When two electric bulbs of $40\, W$ and $60\, W$ are connected in parallel,then:

$A$ circular wire has a current density $J = (2 \times 10^{10} \text{ A/m}^2) r^2$, where $r$ is the radial distance from the center and the wire radius is $2 \text{ mm}$. The potential difference applied across the wire is $50 \text{ V}$. How much energy (in Joules) is converted to thermal energy in $100 \text{ s}$ (in $\pi$)?

The number of electrons flowing per second in the filament of a $110 \,W$ bulb operating at $220 \,V$ is : (Given $e=1.6 \times 10^{-19} \,C$ )

The resistor of resistance $R$ is connected to a $25\, V$ supply and the heat produced in it is $25\, J/s$. The value of $R$ is .......... $\Omega$.

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

The heat produced by a $100\, W$ heater in $2\, minutes$ will be equal to: