The unit $Volt \times Ampere$ represents which physical quantity?

$(a)$ Why is the series arrangement not used for domestic circuits?
$(b)$ Why is tungsten used almost exclusively for the filament of electric lamps?
$(c)$ Why are the conductors of electric heating devices,such as bread toasters and electric irons,made of an alloy rather than a pure metal?
$(d)$ Why are copper and aluminium wires usually employed for electricity transmission?
$(e)$ Why does the cord of an electric heater not glow while the heating element does?

What is the formula to find electric power $P$?

In the following circuits (Figure),heat produced in the resistor or combination of resistors connected to a $12\, V$ battery will be

You are given three bulbs of $25 \, W$,$40 \, W$,and $60 \, W$ marked at $220 \, V$. Which one of them has the lowest resistance?

$A$ cylindrical conductor of length $l$ and uniform area of cross-section $A$ has resistance $R$. Another conductor of length $2l$ and resistance $R$ of the same material has area of cross-section: