• Support PF! Buy your school textbooks, materials and every day products Here!

Light bulb circuit

  • Thread starter lofty28
  • Start date
  • #1
9
0
A DC circuit has resistances of 10Ω, 12Ω, and 10Ω respectively. Also has 2 light bulbs with identical tungsten (resistivity = 5.6* 10^-8) filament bulbs with filament thickness of 12um and length of 1.2cm. The source is a 12V.

what is the power loss over the first light bulb?


I am not entirely sure which equations to use how ever the ones which i thought to use are:
V=RI
P=VI
P=V^2 / R
I am really stuck and dont know how to find the acual power loss. I think my main issue is gather the correct information and implimenting it in the right situation.



I have attempted to find the total, R1+R2+R3= 32Ω
And then i have divided each by the source 12... 2.66A
Can someone please direct me in the right way...? I am gettin quiet frustrated with it!!
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
25,832
249
hi lofty28! :smile:

yes, that's the right method, find the current first, and then find the power through the bulb with that current

(but you'll need to add the resistances of the two bulbs, and add them, before finding the current :wink:)
 

Related Threads for: Light bulb circuit

  • Last Post
Replies
14
Views
24K
  • Last Post
Replies
15
Views
15K
  • Last Post
Replies
10
Views
4K
  • Last Post
Replies
10
Views
52K
  • Last Post
Replies
3
Views
18K
  • Last Post
Replies
1
Views
3K
Replies
14
Views
1K
  • Last Post
Replies
11
Views
3K
Top