Electric light bulbs are normally connected in parallel across the 230 V supply in your house.

Question

Assume you have five of them each rated at 60 W. In a re-wire the

apprentice electrician mistakenly connects them in series. What would the power output of each lamp be now?

Answer 1

You really need a lot more information to do this calculation, as light bulbs are very non linear, with the resistance varying by a factor of 5 or 10 from cold to hot.

But if this is just a book question, we can forget all that...

Resistance of a 60 watt bulb is:

P = E²/R

60 = 230²/R

R = 882 ohms.

Put 5 in series, and the resistance total is 4408 ohms.

Power is E²/R

P = 230²/4408 = 12 watts.

divide that up by 5 bulbs and you get 2.4 watts each, not enough to make them glow.

.

Answer 2

I'll help you out, but you need to do the math. All the lamps in series will be about 440 ohms, total current at 230 volts is about 0.5 amps, total string power is about 115 watts.

You really do need to learn to do such simple problems on your own.

Answer 3

divide the voltage by the number of resistors (bulbs)

but in the usa household wiring is usually 110 volts with separate 220 circuits for heavy loads like stoves, dryers, air conditioners (HVAC)