Got 2 Light Bulbs that are rated 60 Watts at 120 Volts. When in series they have 60 Volts across them with just 0.25 Amps so they are 15 Watts each. When in parallel they got 120 Volts across them with 0.50 Amps so they are 60 Watts each. Doubling the voltage causes the power to be 4 times as high.
