What is the current in each bulb?

  • Thread starter Thread starter aznseal12
  • Start date Start date
  • Tags Tags
    Bulb Current
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 2K views
aznseal12
Messages
1
Reaction score
0
Two 40-watt bulbs are connected in parallel to a 120-volt circuit. What is the current in each bulb?
Choose one answer.
a. 1/4 A
b. 1/3 A
c. 1/2 A
d. 2 A
e. 3 A

I used V = IR and P = V^2/R

My attempt
40 W = 120V^2 / R giving R = 360
1/R + 1/R = 1/Req => 1/360 + 1/360 = 1/Req => Req = 180ohms
V=IR => 120 = 180I => I = 2/3
which is not an answer
 
Last edited:
Physics news on Phys.org


You found the total current (correctly), but the question asks for the current through each bulb.
 


You don't need to calculate resistance here, assume the total current is [tex]I[/tex] , then [tex]I= \frac{80w}{120V}=\frac{2}{3} Amp[/tex], the current in each bulb should be [tex]\frac{1}{3} Amp[/tex]