$1 \, \mu A = \ldots \ldots \ldots \, A$

In an electrical circuit,two resistors of $2\,\Omega$ and $4\,\Omega$ respectively are connected in series to a $6\,V$ battery. The heat dissipated by the $4\,\Omega$ resistor in $5\,s$ will be ........ $J$.

$A$ piece of wire having resistance $R$ is cut into four equal parts. $(a)$ How will the resistance of each part compare with the original resistance? $(b)$ If the four parts are placed in parallel,how will the joint resistance compare with the resistance of the original wire?

$A$ current of $0.5\, A$ is drawn by a filament of an electric bulb for $10$ minutes. Find the amount of electric charge that flows through the circuit. (in $C$)

$(a)$ $A$ Nichrome wire of length $L$ and radius $r$ has a resistance of $10 \, \Omega$. How would the resistance of the wire change when:
$(i)$ only the length of the wire is doubled?
$(ii)$ only the diameter of the wire is doubled? Justify your answer.
$(b)$ Why are the elements of electrical heating devices made up of alloys?

$(a)$ Give reasons why tungsten is used for making the filament of electric lamps.
$(b)$ Why are the heating elements of electrical appliances made up of an alloy rather than a pure metal?