The relationship between the current, voltage and resistance is known as Ohm's Law:
`V = I*r` , where V is voltage, i is current and r is resistance.
Therefore the current through the 240 `Omega` bulb connected to 120-Volt source is
`I=V/r = (120 V)/(240 Omega) = 0.5` Amp
The current is 0.5 Amps.