# What is the current in each bulb?

1. Aug 15, 2011

### aznseal12

Two 40-watt bulbs are connected in parallel to a 120-volt circuit. What is the current in each bulb?
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

Last edited: Aug 15, 2011
2. Aug 15, 2011

### Pi-Bond

Re: Circuits

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

3. Aug 15, 2011

### genxium

Re: Circuits

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