What is meant by $1$ ohm resistance?

Define current. Give its $SI$ unit.

Derive an expression for equivalent resistance when three resistors of resistance $R_{1}, R_{2}$ and $R_{3}$ are connected in parallel.

In a Voltaic cell,what is the direction of the flow of electrons in the external circuit?

An electric iron has a rating of $750\, W; 200\, V$. Calculate:
$(i)$ The current required.
$(ii)$ The resistance of its heating element.
$(iii)$ Energy consumed by the iron in $2$ hours.

$(a)$ Explain how a cell maintains current in a circuit.
$(b)$ In the circuit given below,the resistance of the path $xTy = 2 \, \Omega$ and that of $xZy = 6 \, \Omega$.
$(i)$ Find the equivalent resistance between $x$ and $y$.
$(ii)$ Find the current in the main circuit.
$(iii)$ Calculate the current that flows through the path $xTy$ and $xZy$.