The quantity of charge flowing past a point multiplied by time is current.

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

What is the unit of electric potential difference?

$(a)$ What is the total resistance of $n$ resistors each of resistance $R$ connected in:
$(i)$ series?
$(ii)$ parallel?
$(b)$ Calculate the resultant resistance of $3$ resistors $3 \ \Omega, 4 \ \Omega$,and $12 \ \Omega$ connected in parallel.

The following table provides the resistivity of three samples:

Sample	$A$	$B$	$C$
Resistivity	$1.6 \times 10^{-8} \Omega \cdot m$	$5.2 \times 10^{-8} \Omega \cdot m$	$100 \times 10^{-6} \Omega \cdot m$

Which of them is suitable for heating elements of electrical appliances and why?

Three incandescent bulbs of $100\, W$ each are connected in series in an electric circuit. In another circuit,another set of three bulbs of the same wattage are connected in parallel to the same source. Now,if one bulb in both the circuits gets fused,will the rest of the bulbs continue to glow in each circuit? Give reasons.