Series -
P lamp A = I x V = 1.2 x 48 = 5.76W
5.76W means that the bulb is converting 5.76J of electrical energy to heat & light energy per second.
P lamp B = I x V = 1.2 x 7.2 = 8.64W
Lamp B is brighter because its power indicates its brightness.
Same current as lamp A. Greater resistance, means greater voltage to pass the same current therefor greater power.
Parallel -
P lamp A = I x V = 3 x 12 = 36W
P lamp B = I x V = 2 x 12 = 24 W
Same voltage. Lamp B has less current & less power. Lamp A is brighter than lamp B because it has greater power
