Of the two bulbs in a house, one glows brighter than the other. Which of the two has a larger resistance?

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.

The $I-V$ graphs of two resistors,and their series combination,are shown below. Which one of these graphs represents the series combination of the other two? Give reasons for your answer.

An electric oven hot plate is connected to a $200 \, V$ line. It has two resistance coils $A$ and $B$,each of $30 \, \Omega$,which may be used separately,in series,or in parallel. Find the value of the current required in each of the three cases.

$(a)$ What are the values of $mA$ and $\mu A$ in terms of Ampere $(A)$?
$(b)$ Draw the symbols of a battery and a rheostat.

An electron in a metal is free to move anywhere but cannot leave the metal.