Find the current in the circuit. (in $ A$)

Two light bulbs in the circuit have ratings $A\,[24\ V, 48\ W]$ and $B\,[24\ V, 36\ W]$ as shown in the figure.

Three voltmeters,all having different internal resistances,are connected as shown in the figure. When a potential difference is applied across $A$ and $B$,their readings are $V_1, V_2$,and $V_3$. Choose the correct option.

The current in a simple series circuit is $5.0 \, A$. When an additional resistance of $2.0 \, \Omega$ is inserted, the current drops to $4.0 \, A$. The original resistance of the circuit in $\Omega$ was:

The charge supplied by a source varies with time $t$ as $Q = at - bt^2$. Find the total heat produced in the $2R$ resistor before the current reduces to zero.

In how much time will one litre of ${H_2}$ be collected by a $5\, A$ current? (Given: $Z = 1 \times {10^{ - 8}}\,kg/C$ and density of ${H_2} = 0.09\,kg/{m^3}$)