$A$ current of $1\, A$ is drawn by a filament of an electric bulb. The number of electrons passing through a cross-section of the filament in $16$ seconds would be roughly:

Define power. State the difference between $1$ watt and $1$ watt hour. Establish the relationship between the commercial unit of electric energy and the $SI$ unit of energy. An electric heater rated $1000 \ W / 220 \ V$ operates for $2$ hours daily. Calculate the cost of energy to operate it for $30$ days at the rate of ₹ $5.00$ per $kWh$.

What are the factors on which the resistance of a conductor depends?

Sonika is working with the circuit shown in the figure. There are two open terminals in the circuit: $X$ and $Y$. She has wires made of five different materials: $I, II, III, IV,$ and $V$. She knows that the electric bulb will glow only when wires made of conducting materials are connected across both open terminals. She records her observations in a table. After the experiment,ink spills on the paper,and she loses the information for the third row.

$S.No.$	Material at $X$	Material at $Y$	Electric Bulb ($ON$/$OFF$)
$1$	$I$	$II$	$OFF$
$2$	$I$	$IV$	$ON$
$3$	-	-	$OFF$
$4$	$III$	$V$	$ON$

Based on the remaining information in the table,which materials could be in the third row?

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

What is the unit of resistance?