No current flows between two charged bodies when connected,if they have the same

What is potential difference? Is it a scalar quantity or a vector quantity? Give its $SI$ units.

$A$ thick wire and a thin wire of the same material are successively connected to the same circuit to find their respective resistance. Which one will have lower resistance? Give reason.

Define current,give its mathematical expression. What is its $SI$ unit?

$B_1, B_2$ and $B_3$ are three identical bulbs connected as shown in the figure. When all three bulbs glow,a current of $3\,A$ is recorded by the ammeter $A$.
$(i)$ What happens to the glow of the other two bulbs when the bulb $B_1$ gets fused?
$(ii)$ What happens to the reading of $A_1, A_2, A_3$ and $A$ when the bulb $B_2$ gets fused?
$(iii)$ How much power is dissipated in the circuit when all three bulbs glow together?

An electric bulb of resistance $480 \Omega$ is connected to a $220 \text{ V}$ main. Find the amount of electrical energy consumed in $10 \text{ seconds}$. (in $J$)