Elements of electric toasters and electric irons are made of an alloy rather than a pure metal. Give two reasons to justify the statement.

$A$ bulb is rated $220\;V$ and $100\;W$. What is the resistance of this bulb?

The table given below provides the resistivity of three samples in $\Omega \cdot m$:

Sample	Resistivity $(\Omega \cdot m)$
$A$	$1.6 \times 10^{-8}$
$B$	$7.5 \times 10^{17}$
$C$	$44 \times 10^{-6}$

$(a)$ Which of them is a good conductor? Which is an insulator? Why?
$(b)$ $A$ wire of resistance $4 \ \Omega$ is folded on itself to double its thickness. Calculate the new resistance of the wire.

$1\, \mu A = \dots \dots \dots \,mA$

From the listed electrical devices,which releases heat energy that is not appreciated?

What is the maximum resistance which can be made using five resistors each of $1/5 \ \Omega$ (in $\Omega$)?