Out of the following bulbs rated $40 \ W, 220 \ V$,$60 \ W, 220 \ V$,and $100 \ W, 220 \ V$,which one will glow the brightest when connected in series to a supply of $220 \ V$?

An electric bulb is connected to a $220 \ V$ generator. The current is $0.50 \ A$. What is the power of the bulb?

Define $1$ volt.

$A$ potential difference $V$ is applied across a conductor of length $L$ and diameter $D$. How is the resistance $R$ of the conductor affected,when in turn $(i)$ $V$ is halved,$(ii)$ $L$ is halved,and $(iii)$ $D$ is doubled? Justify your answer in each case.

$(a)$ State the commercial unit of electric energy and find its relation with its $SI$ unit.
$(b)$ The current through a resistor is made three times its initial value. Calculate how it will affect the heat produced in the resistor.
$(c)$ Find the increase in the amount of heat generated in a conductor if another conductor of double resistance is connected in the circuit,keeping all other factors unchanged.

$(a)$ How much current will an electric bulb draw from a $220 \ V$ source,if the resistance of the bulb filament is $1200 \ \Omega$?
$(b)$ How much current will an electric heater coil draw from a $220 \ V$ source,if the resistance of the heater coil is $100 \ \Omega$?