Two bulbs, power, voltage, seres connection

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 2K views
math_maj0r
Messages
14
Reaction score
0

Homework Statement



Two bulbs rated 25 W - 110 V and 100 W - 110 V are connected in series to a 230 V supply. What will happen?
>
>

Homework Equations



p = vi. p = v2/r


The Attempt at a Solution



I am not sure I know how to interpret it correctly. To find the current through bulb 1, I did P1/V1 = 25/110 = .227, and for bulb 2 I did P2/V2 = 100/110 = .909. This can't be right because I1 must equal I2 since they are in series.

If I use the other formula p = v2/r and solve for resistance, i get a really big answer. i think i may be doing something wrong by plugging in 110 for v.

?
 
Physics news on Phys.org
You get a big answer ?
How much ?
 
First, consider each bulb separately.

If you connect the 25W bulb across a 110V source (as it was designed for), what is the resistance?