Of which physical quantity is the $joule/coulomb$ a unit?

$A$ wire connected to a bulb does not glow,whereas the filament of the bulb glows when the same current is passed through them. Why?

$A$ piece of wire of resistance $6 \, \Omega$ is connected to a battery of $12 \, V$. Find the amount of current flowing through it. Now,the same wire is redrawn by stretching it to double its length. Find the resistance of the new (redrawn) wire.

$(a)$ Name an instrument that measures electric current in a circuit. Define the unit of electric current.
$(b)$ What do the following symbols mean in an electric circuit?
$(c)$ Draw a closed circuit diagram consisting of a $0.5\, m$ long nichrome wire $XY$,an ammeter,a voltmeter,four cells of $1.5\, V$ each,and a plug key.

$A$ wire of resistance $10 \, \Omega$ is bent in the form of a closed circle. What is the effective resistance between the two points at the ends of any diameter of this circle?

$1\, mA = \dots A$