Electric Circuit

Thread Starter


Joined Mar 13, 2004
i have a question B)

what is the difference in brightness when two lights set in series is compared with the brightness one light in a circuit(series)?


What is the difference in brightness when two lights set in parallel is compared with the brightness of one light in a circuit

i would be really thankful if you can answer my question. my e-mail is mercury_yang@hotmail.com :)


Joined Feb 26, 2004
Hi mercury:
In series the current is constant and the Voltage is relative to the amount of resistance of each load and as Kirchoff states the total voltage will equal to the sum of the voltage drops across each load where in Parallel the Voltage will remain constant across the loads and the current will be the sum of all the load currents. So say to bulbs of each having 50 ohms in series with other placed on the 100 volt supply will cause a 1 amp current to flow and the voltage drop will be 50 volts on each bulb, thus each bulb will produce 50 watts output totalling a 100 watt load. Now in parallel we will have 2 50 ohm bulbs across 100 volt supply and this will cause a 25 ohm total load and will cause a 4 amp current flow and each bulb will be drawing 2 amps thus each bulb will operate at 200 watts per and the total will be 400 watts of power. AS you can see the there is 4 times the power used in the parallel circuit than in the series one. Look at the tutorials here on the ohms laws and series and parallel circuits too.
Good luck