What is the other name of the commercial unit of electrical energy?

In the figure given below,$A, B$,and $C$ are three ammeters. The ammeter $B$ reads $0.5\, A$. (All the ammeters have negligible resistance.) Calculate:
$(i)$ the readings in the ammeters $A$ and $C$.
$(ii)$ the total resistance of the circuit.

When a high resistance voltmeter is connected directly across an electric bulb,its reading is $2 \ V$. An electric cell is sending a current of $0.4 \ A$ (measured by an ammeter) in the electric circuit.
$(a)$ Draw the circuit.
$(b)$ Find the resistance of the electric bulb.
$(c)$ State the law that is applied for making these calculations. If a graph is plotted between $V$ and $I$,show the nature of the graph obtained.

How many electrons will there be in $1.6 \ C$ charge?

Why do the wires connecting an electric heater to the mains not glow while its heating element does?

$A$ current of $1 \ A$ flows in a series circuit containing an electric lamp and a conductor of $5 \ \Omega$ when connected to a $10 \ V$ battery. Calculate the resistance of the electric lamp. Now,if a resistance of $10 \ \Omega$ is connected in parallel with this series combination,what change (if any) in the current flowing through the $5 \ \Omega$ conductor and the potential difference across the lamp will take place? Give reason.