Two light bulbs in a series circuit...?

Question

If there are two light bulbs in series, and the resistance of each is 10 Ohms, is the total resistance of the circuit 20 Ohms? Is this the value used in Ohm's Law?

Answer 1

Yes... In series circuit you add

Answer 2

Hmm, If you use these light bulbs as resistors, current must be small enough not to heat up the filaments so that their resistances change due to heat is negligible.
Otherwise if you light up the bulb the resistance increase due to heat.We can only know the actual resistance by ohm's law calculation.
Let say your light bulb has 10 ohms resistance,10V.If you connect two bulbs in series and connect to 20 V power, actual current is not 1Ampere it is smaller than you calculated.In order to determine the actual resistance,you need to measure the actual current and calculate R=V/I.
Another way is if you know the wattage of the bulb you can roughly calculate the resistance during light up.
P=V^2 / R so R = V^2/P

Answer 3

That would be correct except for you did not factor in the resistance of the conductor leading to the light bulbs, between the light bulbs, and returning from the light bulbs.

But the conductor resistance is extremely small, so unless the conductors are long, it will not be of any concern in your calculation.

Answer 4

yes

Answer 5

you said "power source" I^2R + I^2R is total power in both series and parallel cases => "A" /*************************************... had you said "voltage source" V^2 / R would differ => "C" had you said "current source" => "B" there is no "source" issue which would yield "D" as answer (you could have a "bad socket" ... nahhh, that's beyond the scope of the question .... little green men standing on the backs of turtles, etc ... cookie monster and Bigfoot)