A rigid container with thermally insulated walls contains a coil resistance   $\text{100}\Omega$ carrying current 1 A change in internal energy after 5 minutes will be

work done(dW) = heat energy produced in the resistor

$\text{dW=dU}$=change in internal energy

$\begin{array}{rcl} & & {\text{heat energy produced in a resistor is dW=i}}^{\text{2}}\text{Rt}\\ given current i& =& 1A;resis\tan ce R=100\Omega ;time t=5x60=300s \\ & & substitute given values in above equation\\ \mathrm{heat} \mathrm{energy} \mathrm{produced} \mathrm{in} a \mathrm{resistor} & =& \text{1}\times \text{100}\times \text{300}\\ & \Rightarrow & change in internal energy =30000J\\ & \Rightarrow & change in internal energy \text{= 30\hspace{0.17em}kJ}\end{array}$